A URL has the format 
type-of-service://site-of-service[/path] 

The type-of-service is one of 

http	--hypertext markup language 
ftp 	--file transfer protocol
gopher --gopher server
news --Usenet newgroups. With this service omit the '//'.
mailto --E-mail. The '//' may be omitted and the site is an 
e-mail address.