What does “category” in the manifest mean?

Question

The documentation says you can specify a custom category.

• When, why and how would you do it?
• What would be the use of it?

Answer 1

I'm kinda a noob to Android still, although I have programming experience otherwise.. It says a custom category in your own namespace. I'm guessing that if you are programming multiple apps and you want one app to run another app, you could use a custom category for your intent to force the phone to find your other app to catch the intent with?