The Importance of Tests in Applications

I was previously developing applications in Visual Basic and Delph. And by the time I started studying Ruby and Ruben Rails, I didn't know the importance of putting tests in the code. The amount of bugs that we had were big, like it was huge. We really wanted to get things done very fast. But when the code causes these problems, like bugs and stuff like that, or when the low quality of the code makes it so you can't get a release out and all that stuff, then of course, users care about that.