Automated Unit testing - why? what? which?

Question

I am a C# winforms developer with an experience of around a year. The only unit testing that I have been doing till now has been manual. I have thinking about following for

Answer 1

The why for automated unit testing is simple: because as your code grows, it will take longer and longer to do manual testing, which means you are less and less likely to do it.

By automating the tests, you make them convenient to run, so they will be run.