Manual testing: Everything you need to know

Say you’re testing a checkout flow for a shopping app when you notice that the payment button hides behind the keyboard. It works perfectly in code, but users would struggle to tap it. This is manual testing’s strength: catching the issues automation misses.

In this post, we’ll look at what manual testing is, its benefits, its drawbacks, and how it compares with and complements automated tests.

Manual testing is the process where testers execute test cases manually without the assistance of automation tools

What is manual testing?

As IBM defines it, “Manual testing is the process where testers execute test cases manually without the assistance of automation tools.” In simpler terms, that means testers go through the software by hand. They click buttons, fill out forms, and try to break things. They’re looking for bugs, sure, but also checking if the flow makes sense for users.

How did this all start?

Manual testing’s been around since the 1940s. Back then, programmers would mostly test their code by debugging (as noted by IBM’s “History of software testing”) until proper test cases and structured methods began emerging in the 1980s. By that time, testing became its own discipline, focused on ensuring quality instead of just fixing bugs.

After that, automation was introduced in the 1990s, and finally, we could let machines handle repetitive checks while testers focused on user experience and complex workflows.

Why is manual testing important?

People often call manual testing old-fashioned, but it’s still one of the most practical ways to find issues and catch edge cases that tools could miss, plus it also helps teams see the product the way users experience it. Here’s why it is important:

Leaves room for human judgment

Manual testing leaves more space for human judgment and observation. A tester can easily notice small things like clicking a button while it’s still loading, or when the onboarding flow is confusing for first-time users, both situations that automation mostly won’t cover.

Easily adapts to changing requirements

Manual testers don’t need scripts, so they can quickly adapt when requirements shift. A new feature dropped? They jump in and explore the flow to find issues. This makes manual testing invaluable for MVPs and fast-paced projects where everything’s still evolving.

Tests real user behavior

Manual testing lets you explore actual user patterns, not just ideal scenarios. Take a payment page, for example, where users can sometimes get distracted. They might fill in their card details, then answer a phone call, and then return 15 minutes later to submit.

Does their session expire for security reasons? Or worse, does it still allow them to submit after such a long time? These unexpected situations are rarely covered in automated test scripts.

Catches UI and usability issues

Manual testers notice when things seem wrong, like when buttons are too close together, text overlaps, or popups block your clicks.

If a payment button gets covered by the keyboard, automation would still pass the test because it only checks if the button works in code, not how it looks or behaves on a real device. But in manual testing, you’d spot right away that users can’t even tap the button.

Works better for complex interactions

Dragging, dropping, resizing, and scrolling through nested menus are painful interactions to automate. Manual testing works better here because you immediately notice when something’s clunky. If there’s a slight lag or awkward gesture, you can catch it instantly while using it.

Manual testing complements other testing approaches rather than replacing them

Where does manual testing fit into the broader testing strategy?

Manual testing complements other testing approaches rather than replacing them. Teams typically run automated tests with each code deployment to catch bugs quickly.

However, before major releases, manual testers review the application to verify end-to-end workflows and examine things that automation often overlooks (such as text alignment issues, color contrast, performance lag, and navigation flow).

This becomes valuable during UAT (user acceptance testing), where human evaluation matters. Overall, the automated and manual combination ensures that both technical accuracy and practical usability are addressed before the software reaches end users.

Types of manual testing

Manual testing comes in many forms; some are planned, some are instinctive, and they often overlap. For instance, you might do exploratory testing during UAT or run test cases in an end-to-end flow.

1. Manual test case execution

In this testing approach, you work through a written checklist of steps and inputs, then compare results against expectations.

For example, when testing a login form, you try incorrect credentials, wrong passwords, or invalid emails. Then, you check if error messages show up properly and also click the Forgot Password link to confirm that it works. It’s a straightforward, methodical test that follows a plan.

2. Exploratory testing

Here, you test with just your curiosity, trying different paths to see what happens. You might type some special characters into a search bar or open five tabs at once and identify if the app freezes or if any other unexpected issue occurs.

3. Usability testing

Usability testing checks how easy and natural the app feels for users. Testers might move through the onboarding flow, for example, and if they can’t easily find the Next button, something’s wrong, and they will report it.

4. End-to-end testing

In end-to-end testing, you test like a real user, going through the whole flow from start to finish. For example, in an online store, you might add items to the cart, apply a coupon, pay, and check if the confirmation email arrives. Everything should connect smoothly.

5. Regression testing

In fast-moving projects or early stages where automation scripts aren’t stable yet, regression testing is often done manually to quickly check that existing features haven’t broken after an update or bug fixes.

For example, a dashboard update might stop your notifications from showing because the new code overwrote a shared function or altered the data-loading mechanism.

6. Ad-hoc testing

Ad-hoc testing is more random and based on instinct. For instance, while testing a food delivery app, a tester might add the same meal three times, then remove one after applying a coupon (something mostly unexpected). Actions like this often show subtle bugs that most formal tests might not cover.

7. Compatibility testing

Here, you’re checking if your app works everywhere users might use it. A page might look perfect in Chrome, but doesn’t load in Safari because of how Safari processes cookies. With compatibility testing, you test everywhere to catch these inconsistencies.

8. User acceptance testing (UAT)

In UAT testing, users or clients test the app to see if it meets their needs. Although it’s manual, its focus is on the business value, not bugs. A manager might test an expense system by submitting a claim and checking if it shows up in his reports. It’s done before release to confirm that the system works for the people who’ll use it.

Manual testing vs. automated testing

Manual and automated testing both aim to find bugs and make software reliable, but they do it in very different ways. Here is how they compare:

When to use manual testing

• Use manual testing when you’re expecting a lot of changes in the application. It’s easier to adjust and test things by hand instead of updating scripts all the time.
• It works best for ad-hoc or exploratory testing, where you’re just trying different things to see what breaks.
• Also, if it’s a small project like a demo app, or there’s not much time or resources for automation, go for manual testing.

When to use automation testing

• Go for automation when the same tests need to be run again and again, like regression or smoke tests. Once you set it up, it saves a lot of time.
• It’s perfect for big projects with many features, since testing everything by hand would be time-consuming.
• If you need quick feedback from your tests, go for automation.

In manual testing, testers can adapt easily when features or requirements change

Benefits of manual testing

Manual testing is flexible and helps catch issues that tools can’t easily spot. Here are some key benefits:

1. Finds user interface (UI), user experience (UX), and usability bugs that automation might miss.
2. In manual testing, testers can adapt easily when features or requirements change.
3. It has a lower setup cost, as there is no need for tools or test scripts.
4. It’s great for exploratory or ad-hoc testing where scenarios aren’t predefined.
5. It helps improve test coverage when combined with automated tests to find subtle bugs.

Drawbacks of manual testing

Manual testing is useful, but it also has some downsides you should know about. It can be slow, tiring, and sometimes less consistent. Here are some common drawbacks:

1. Different testers may interpret requirements or UI differently. So what one tester sees as a Pass, another may see as a Fail.
2. It’s prone to human error because, as testers get tired, they may miss details, skip steps, or misinterpret requirements.
3. It’s repetitive and becomes boring. Doing the same tests over and over is monotonous, which increases the chances of mistakes or oversight.
4. Running tests by hand for each scenario takes a lot of time, especially in a big project with many features.
5. Sure, manual testing costs less upfront, but if you keep doing it release after release on a large application, it ends up being expensive, costing you a lot of time and money.

Conclusion

Automation handles a lot and does it quickly, but it doesn’t think like an actual person using your software. Human testers spot things that look off or awkward. They catch usability issues that automation completely misses, like confusing layouts, slow responses, or unexpected user behavior.

Smart teams run both types of testing. Use automation to run repetitive checks and get fast feedback, then bring in manual tests to go through the app and find issues that’ll frustrate users. This combination will ensure that your software functions well and is reliable for everyday use.

This post was written by Inimfon Willie. Inimfon is a computer scientist with skills in JavaScript, Node.js, Dart, Flutter, and Go Language. He is very interested in writing technical documents, especially those centered on general computer science concepts, Flutter, and backend technologies, where he can use his strong communication skills and ability to explain complex technical ideas in an understandable and concise manner.