.*? instad of .*

From: Zhidian Du (zdu_at_cs.nmsu.edu)
Date: 11/27/03 

Date: 26 Nov 2003 21:37:31 -0800

I read a program that strip tags of html

while(<>){

  s/<.*?>//gs

}

I am courious why it uses .*?, not .*

Another question, while(<>) read one line at a time or a couple lines of a time?
How do I know it?

Thanks.

Z. Du