Manual testing means starting your application and using it. It takes up a lot of time, not just because you'll be actually using the application, but also because it takes time to get test environments set up and primed with the relevant test data.
For this reason, it's important to avoid manual testing where possible. There are, however, times when it's necessary, as we'll discover in this section.
Since you're engaging with your own creative work, you are undoubtedly interested to find out how it performs. You should certainly take the time to do this, but think of it as downtime and a chance to relax, rather than a formal part of your development process.
There is always a temptation to manually test software after each feature is complete, just to verify that it actually works. If you have to do this a lot, consider how much confidence...