I believe it makes it easier to partition traffic and different subdomains can have different configurations. See also http://stackoverflow.com/questions/91897

I believe it makes it easier to partition traffic and different subdomains can have different configurations. See also http://stackoverflow.com/questions/918971/when-should-i-use-or-avoid-subdomains http://stackoverflow.com/questions/918971/when-should-i-use-... and http://www.mattcutts.com/blog/subdomains-and-subdirectories/ http://www.mattcutts.com/blog/subdomains-and-subdirectories/