A bit of sarcasm, yes. Your note contained no information to prompt a meaningful answer.
The best way to query a behavior is to create an example app, and explain what behavior you are seeing, and what behavior you expect to see.
Asking open-ended questions like "how does validation work" is too broad a topic, and would likely not answer your actual question. So rather than write a 10 page explanation I thought I would prompt you to write a better question. You (marginally) did that, however if you follow the directions above I can give you a more meaningful answer.