Male hair loss usually comes from male pattern baldness.  It is a genetic condition which is passed on through family lines, and it consists of the body producing too many androgens which shrink the hair follicles squeezing hair out essentially speaking.  The entire strand shrinks over time, and eventually it just doesn’t grow anymore.  It is generally seen in men around 20-30 years of age first, and of course it keeps getting worse as you get older or sometimes it just stays around as you get older. 

In general terms, it tends to form a U on the hairline.  Some have made it somewhat fashionable by simply shaving their heads before it really gets that far so it looks like they did it on purpose, and some obviously think that it looks distinguished.  But there are of course plenty who don’t want to lose hair and they don’t want to deal with it.  So currently, there are quite a few different treatment options available to the common user for their greater needs.  They don’t work for everybody.  

But of course they work for a significant number of users, or else they wouldn’t sell after a while.  There are over the counter and prescription options both, and it depends on your case as to which one will work best for you.