What is Software Testing? Definition, Types, and Tools

Software is literally carrying our modern world. They are so deeply entrenched in our life that a single bug is enough to cause rippling damage across industries. Without software testing, the Y2K event might have happened and caused damage in the billions of dollar. 

Luckily, we are not living in that timeline. Kudos to software testers of the 90s.

To the general public, software testing is a lesser-known part of the tech industry. However, without QA teams, bugs would have destroyed the applications we use on a daily basis. In this article, we'll shed light on the software testing field, how you can do software testing, and the most effective tools to do it.

What is Software Testing?

Software testing is the process of checking if the quality, functionality, and performance of a software meets expectations and works as expected.

To test a software, testers execute it under controlled conditions, across a wide range of scenarios, environments, and user interactions to see if there are any defects arise during the process.

Why is Software Testing Important?

The road of software development is bumpy, and products can always be vulnerable to bugs and defects. It is necessary to ensure that software works as expected before being released to the market. Here are several reasons why software testing is essential:

1. Detecting defects for the development team to address

The first goal of testing is to uncover bugs and defects.

As modern software is built from highly interconnected components that must work together seamlessly to deliver the intended functionality, one single broken component is enough to create a ripple effect that breaks the app.

The sooner the broken code is fixed, the smaller the impact. A good testing process in place ensures that a higher quality and more reliable product is always delivered on time.

2. Maintain and enhance product quality

When we talk about quality, we’re referring to features and performance that not only meet but surpass customer expectations. A high-quality application doesn’t just function as intended—it consistently delivers a superior user experience.

In this light, software testing becomes the foundation of quality for several reasons:

Maintain:

• Preserve stability: Regression testing ensures that quality remains intact, even as new code is added.
• Safeguard key areas: Ongoing usability, compatibility, and security testing keep critical aspects of the software running smoothly.
• Inform improvement: Testing provides the development team with actionable insights, enabling them to update documentation and refine the product continuously.

Enhance:

• Increase reliability: Testing helps identify and resolve bugs, making the software more dependable.
• Drive optimization: Testing highlights areas for improvement and performance enhancements.
• Ensure expected functionality: It verifies that all features are operating as designed and intended.
• Stay user-focused: Testing helps align the software with evolving user needs and feedback.
• Enable broad compatibility: It guarantees the software performs well across different platforms, devices, and environments. 

3. Improve customers' trust and satisfaction

Thorough software testing is the secret sauce to earning your customers’ trust. Sure, we all know that no software is ever completely bug-free—but that’s not the point. What really matters is delivering a product that’s stable, reliable, and consistently hits the mark when it comes to user needs. Over time, this builds a lasting positive experience that keeps users coming back.

By embracing software quality management best practices, you're sending a clear message to stakeholders and customers: this product has been tested, refined, and is ready to perform, no matter what. It’s about showing them they can count on your software, again and again

4. Identify vulnerabilities that can save company costs and even human lives

Financial, medical, legal, and other YMYL (Your Money Your Life) software handle sensitive, high-stakes information. For applications in these fields, there’s zero room for crashes, data corruption, or system failures—even on a small scale—because people's lives and well-being are on the line. A single error in these systems could lead to irreversible damage, not to mention putting the company at risk for costly litigation.

That’s where software testing comes in, acting as the safety net that protects companies from these risks. It ensures that these critical systems perform flawlessly, safeguarding both the users and the business.

Types of Software Testing

Different types of software testing can be classified into multiple categories based on test objectives, test strategy, and deliverables. Currently, there are two major software testing types that Quality Assurance professionals frequently use, including:

• Functional testing: a type of software testing to verify whether the application delivers the expected output.
• Non-functional testing: a type of software testing to verify whether the non-functional aspects of an application (e.g., stability, security, and usability) are working as expected.

These umbrella terms encompass a wide range of testing types, each serving only a specific purpose. These are the main types of functional testing:

• Unit testing: a type of testing done on an individual unit in isolation from the rest of the application. A unit is the smallest testable part of any software, usually responsible for only a very targeted set of functionalities. 
• Integration testing: a type of testing where individual units or components are combined and tested as a group to ensure they work together as expected.
• Acceptance testing: a type of testing to evaluate the application against real-life scenarios
• Visual testing: a type of testing to verify the Graphical User Interface (GUI) to ensure that it is presented to users as expected 

Similarly, under Non-functional Testing, there are also many common testing types, each with different objectives and strategies:

• Security Testing: Testing that checks if the software is secure and protects against unauthorized access or threats.
• Performance Testing: Testing that assesses how well the software performs in terms of speed, stability, and resource usage.
• Load Testing: A type of performance testing that evaluates how the software handles expected and peak loads.
• Usability Testing: Testing that measures how user-friendly and easy-to-use the software is.
• Compatibility Testing (or Cross-browser testing): Testing that ensures the software works correctly across different platforms, devices, or environments.

The decision to use which of these types of software tests depends on the test scenarios, resource availability, and business requirements. 

Learn more: What is Functional Testing? Definition, Tools, Best Practices You Should Know 

Approach to Software Testing

Testers have two approaches to software testing: manual testing vs automation testing. Each approach carries its own set of advantages and disadvantages that they must carefully consider to optimize the use of resources.

• Manual Testing: Testers manually interact with the software step-by-step exactly like how a real user would to see if there are any issues coming up. Anyone can start doing manual testing simply by assuming the role of a user. However, manual testing is really time-consuming, since humans can't execute a task as fast as a machine, which is why we need automation testing to speed things up.
• Automation Testing: Instead of manually interacting with the system, testers leverage software using tools or write automation scripts that interact with the software on their behalf. The human tester only needs to click the “Run” button and let the script do the rest of the testing.

Manual Testing vs. Automated Software Testing: Which One to Choose?

When starting any software testing project, the testing team and development team must sit together and develop a test plan, outlining which areas to test manually and which areas to leverage automation testing. A hybrid approach should give testers the benefits of both types, as shown in the comparison table below:

Read More: Automated Testing vs Manual Testing: A Detailed Comparison

Software Testing Life Cycle

Many software testing initiatives follow a process commonly known as Software Testing Life Cycle (STLC). The STLC consists of 6 key activities to ensure that all software quality goals are met, as shown below:

1. Requirement Analysis

In this stage, software testers work with stakeholders involved in the development process to identify and understand test requirements. The insights from this discussion, consolidated into the Requirement Traceability Matrix (RTM) document, will be the foundation to build the test strategy.

There are 3 main people (the tres amigos) involved in the process:

1. Product Owner: Represents the business side and wants to solve a specific problem.
2. Developer: Represents the development side and aims to build a solution to address the Product Owner's problem.
3. Tester: Represents the QA side and checks if the solution works as intended and identifies potential issues.

To ensure the highest level of understanding between stakeholders, QA teams can employ BDD testing, an Agile approach to software testing where simplicity is valued. Ensuring testability is crucial during the design phase to avoid ambiguous requirements that can lead to invalid software tests.

After that, testers and developers have to collaborate to understand the feasibility of implementing business requirements. If these requirements can not be met within the given constraints, limitations, or resources, they will need to discuss with the business side (either the Business Analyst, Project Manager, and/or the client) to make adjustments or seek alternative solutions.

2. Test Planning

After thorough analysis, a test plan is created. Test planning involves aligning with relevant stakeholders on the test strategy:

• Test objectives: Define attributes like functionality, usability, security, performance, and compatibility.
• Output and deliverables: Document the test scenarios, test cases, and test data to be produced and monitored.
• Test scope: Determine which areas and functionalities of the application will be tested (in-scope) and which ones won't (out-of-scope).
• Resources: Estimate the costs for test engineers, manual/automated testing tools, environments, and test data.
• Timeline: Establish expected milestones for test-specific activities along with development and deployment.
• Test approach: Assess the testing techniques (white box/black box testing), test levels (unit, integration, and end-to-end testing), and test types (regression, sanity testing) to be used.

For a greater degree of control over the project, software testers can add a Contingency plan to adjust the variables in case the project moves in an unexpected direction.

Read more: How to write a test plan? A detailed guide

3. Test Case Development

After defining the scenarios and functionalities to be tested, we'll start writing the test cases.

Here's what a basic test case looks like:

Can you guess what's the test case about? That's right, a test case to check the login functionality of Etsy. When writing a test case, make sure to include the components as shown in the table. That should give you (and your teammates) a good idea of what's being tested, what to expect, and what to troubleshoot when a bug is actually found.

Test case development is closely tied up with test case management. Even if you're just using a spreadsheet to note your test case, you're still doing test case management (only in the most primitive sense).

For manual test cases, test management tools like Xray can be used to note down details of what was performed, the results, findings, and suggestions for developers to reproduce those bugs. For automated tests, intuitive UIs provided by tools like Katalon, Ranorex, or TestComplete are available. Open-source options like Selenium, Cypress, and Playwright are also popular for building custom frameworks.

The actual number of test cases to be executed depends a lot on the complexity of the system under test. A good tester is one who can think of creative ways to break a system, so when developing your test cases, try to put yourself in the mindset of someone who has absolutely no idea how that system works and find as many ways to go wrong with it as possible.

4. Test Environment Setup

This step can be done in parallel with Test Case Development. A test environment is the software and hardware configurations under which the application is tested, including a database server, front-end running environment, browser, network, hardware, etc.

Let's say you want to test a mobile app. You'll need:

• Development environment where developers build, debug, and run early-stage tests on the mobile app:
  • Mobile development platforms (e.g., Xcode for iOS, Android Studio for Android).
  • Simulators/emulators for initial testing on different virtual devices.
  • Local databases and API mock services for early integration testing.
  • Continuous Integration (CI) system to automatically run unit and integration tests after each build.
• Physical devices to identify issues that simulators might miss:
  • A range of physical devices covering different models, screen sizes, and hardware capabilities (e.g., iPhone 12, Galaxy S21, Google Pixel).
  • iOS and Android operating system versions to check compatibility (e.g., iOS 14, Android 10, 11).
  • Tools like Appium or Katalon Studio for automating tests across multiple devices.
• Emulation environment to quickly test different devices and operating systems without needing physical devices:
  • Emulators for Android (Android Studio) and simulators for iOS (Xcode).
  • Multiple configurations of screen resolutions, RAM sizes, and CPU speeds to replicate different device conditions.
  • Debugging tools built into development environments like Xcode or Android Studio.

5. Test Execution

With clear objectives in mind, the QA team writes test cases, test scripts, and prepares necessary test data for execution. Tests can be executed manually or automatically. After the tests are executed, any defects found are tracked and reported to the development team, who promptly resolve them.

During execution, the test case goes through the following stages:

1. Untested: The test case has not been executed yet at this stage.
2. Blocked/On hold: This status applies to test cases that can’t be executed due to dependencies like unresolved defects, unavailable test data, system downtime, or incomplete components.
3. Failed: This status indicates that the actual outcome didn’t match the expected outcome. In other words, the test conditions weren’t met, prompting the team to investigate and find the root cause.
4. Passed: The test case was executed successfully, with the actual outcome matching the expected result. Testers love to see a lot of passed cases, as it signals good software quality.
5. Skipped: A test case may be skipped if it’s not relevant to the current testing scenario. The reason for skipping is usually documented for future reference.
6. Deprecated: This status is for test cases that are no longer valid due to changes or updates in the application. The test case can be removed or archived.

Read More: A Guide To Understand Test Execution

6. Test Cycle Closure

Before we get to the polished test report, we first have the test log—essentially a chronological record of every testing activity in a session. Think of it as the rough draft of a test report. While it provides key data, it’s still pretty basic. QA teams use this raw information to create a more structured and detailed test report.

Take this test log screenshot, for example. It does a solid job at keeping testers in the loop about their project's current state. Let’s break it down:

• Execution environment: This includes key details like the admin ID of the machine used for testing, the operating system, and the browser. All crucial for understanding the test environment.
• Test execution log: It provides two levels of info:
  • Test suite: Here, we see "healthcare-tests - TS_RegressionTest," indicating a regression test suite for a healthcare app. The description tells us that the tests focus on logging in and booking an appointment after successful login.
  • Test case: On a more granular level, we see the first test case—TC1_Verify Successful Login. The goal is to check if login works, and the timestamp confirms when the test ran. Status? Passed! Below, you’ll find each test step clearly laid out.
     

A test log is great for day-to-day tracking, but a test report takes it to the next level. You need more than just raw data—you need insights, visuals, and analysis. So, what makes a good test report?

1. Visualizations: Charts, graphs, and diagrams bring your data to life, making it easy to spot trends and patterns.
2. Monitoring: Keep tabs on project pace, with delivery countdowns and pass/fail ratios for each build.
3. Performance: Track performance trends like execution times and success rates.
4. Comparative analysis: Compare results across different software versions to identify improvements or regressions.
5. Recommendations: Provide actionable insights on which areas need debugging attention.

Software testers will gather to analyze the report, evaluate the effectiveness, and document key takeaways for future reference.

Popular Software Testing Models

The evolution of the testing model has been in parallel with the evolution of software development methodologies.

1. V-model

In the past, QA teams had to wait until the final development stage to start testing. Test quality was usually poor, and developers could not troubleshoot in time for product release. 
 

The V-model solves that problem by engaging testers in every phase of development. Each development phase is assigned a corresponding testing phase. This model works well with the nearly obsolete Waterfall testing method.

On one side, there is “Verification”. On the other side, there is “Validation”.

• Verification is about “Are we building the product right?”
• Validation is about “Are we building the right product?”

2. Test Pyramid model

As technology advances, the Waterfall model gradually gives way to the widely used Agile testing methods. Consequently, the V-model also evolved to the Test Pyramid model, which visually represents a 3-part testing strategy.

 

Most of the tests are unit tests, aiming to validate only the individual components. Next, testers group those components and test them as a unified entity to see how they interact. Automation testing can be leveraged at these stages for optimal efficiency. 

Finally, at the UI testing stage, testers focus on the UX and UI of the application.

3. The Honeycomb Model

The Honeycomb model is a modern approach to software testing in which Integration testing is a primary focus, while Unit Testing (Implementation Details) and UI Testing (Integrated) receive less attention. This software testing model reflects an API-focused system architecture as organizations move towards cloud infrastructure.

Is Automated Testing Making Manual Testing Obsolete?

Automated testing takes software testing to the next level, enabling QA teams to test faster and more efficiently. So is it making manual testing a thing of the past?

The short-term answer is “No”.

The long-term answer is “Maybe”.

Manual testing still has its place in the software testing world. We need humans to evaluate the application’s UX, supervise automation testing, and intervene when necessary. However, AI technology is gradually changing the landscape. Smart testing features have been added to many automated software testing tools to drastically reduce the need for human intervention. 
 

In the future, we can expect to reach Autonomous Testing, where machines completely take control and perform all testing activities. There will be absolutely no need for humans except for the development of testing algorithms. Many software testing tools have leveraged LLMs to bring us closer to this autonomous testing future.

Top Software Testing Tools With Best Features

1. The Katalon Platform

The Katalon Platform allows QA teams to author web, mobile, and desktop apps and UI and API automated tests, execute those tests on preconfigured cloud environments and maintain them, all in one unified platform, without any additional third-party tools. The Katalon Platform is among the best commercial automation tools for functional software testing on the market. 

• Test Planning: Ensure alignment between requirements and testing strategy. Maintain focus on quality by connecting TestOps to project requirements, business logic, and release planning. Optimize test coverage and execute tests efficiently using dynamic test suites and smart scheduling.
• Test Authoring: Katalon Studio - a product within the Katalon Platform portfolio - combines low-code simplicity with full-code flexibility (this means anyone can create automation test scripts and customize them as they want). Automatically capture test objects, properties, and locators to use. 
• Test Organization: TestOps organizes all your test artifacts in one place: test cases, test suites, environments, objects, and profiles for a holistic view. Seamlessly map automated tests to existing manual tests through one-click integrations with tools like Jira and X-ray.
• Test Execution: Instant web and mobile test environments. TestCloud provides on-demand environments for running tests in parallel across browsers, devices, and operating systems, while handling the heavy lifting of setup and maintenance. The Runtime Engine streamlines execution in your own environment with smart wait, self-healing, scheduling, and parallel execution.
• Test Execution: Real-time visibility and actionable insights. Quickly identify failures with auto-detected assertions and dive deeper with comprehensive execution views. Gain broader insights with coverage, release, flakiness, and pass/fail trend reports. Receive real-time notifications and leverage the 360-degree visibility in TestOps for faster, clearer, and more confident decision-making.

Download Katalon and Witness its Power in Action

Check out a video from Daniel Knott - one of the top influencers in the software testing field - talking about the capabilities of Katalon, and especially its innovative AI features:

2. Selenium

Selenium is a versatile open-source automation testing library for web applications. It is popular among developers due to its compatibility with major browsers (Chrome, Safari, Firefox) and operating systems (Macintosh, Windows, Linux).

Selenium simplifies testing by reducing manual effort and providing an intuitive interface for creating automated tests. Testers can use scripting languages like Java, C#, Ruby, and Python to interact with the web application. Key features of Selenium include:

• Selenium Grid: A distributed test execution platform that enables parallel execution on multiple machines, saving time.
• Selenium IDE: An open-source record and playback tool for creating and debugging test cases. It supports exporting tests to various formats (JUnit, C#, Java).
• Selenium WebDriver: A component of the Selenium suite used to control web browsers, allowing simulation of user actions like clicking links and entering data. 

Website: Selenium

GitHub: SeleniumHQ

3. Appium

Appium is an open-source automation testing tool specifically designed for mobile applications. It enables users to create automated UI tests for native, web-based, and hybrid mobile apps on Android and iOS platforms using the mobile JSON wire protocol. Key features include:

• Supported programming languages: Java, C#, Python, JavaScript, Ruby, PHP, Perl
• Cross-platform testing with reusable test scripts and consistent APIs
• Execution on real devices, simulators, and emulators
• Integration with other testing frameworks and CI/CD tools

Appium simplifies mobile app testing by providing a comprehensive solution for automating UI tests across different platforms and devices.

Website: Appium Documentation

Conclusion

Ultimately, the goal of software testing is to deliver applications that meet and exceed user expectations. A comprehensive testing strategy is one that combines the best of manual and automation testing.