How to find tags file in a recursive way?

[Weihua Jiang]

That is, emacs will search for tags file in current directory. If not
found, it will search in parent directory and so on. This is a
functionality VIM provided. I find it is quite useful when I
processing deep directories.

How to use such feature in emacs? I get vtags.el from emacswiki. It is
claimed to have such capability. However, I don't know how to use it.
Or, is there other ways to meet my needs?

thanks
Weihua