www / http

[mark_c]

Why dp some urls have www in front and some have only the http? And some don't use http? Sometimes it appears and sometimes it doesn't. Is this related to some sites being Internet and some being on the Web.

Might seem like 'tard question but I can't find an answer anywhere.

TIA.

[robertmillar]

All urls will have http://, https;// or something similar as a prefix  It is a protocol (a set of operating rules to send files back and forth.  
More info at this link:

www.teachersfirst.com/tutorial/webintro.htm#WWW

or this one

http://teachersfirst.com/tutorial/webintro.htm#WWW

[mark_c]

Hey thanks RobertMillar but I don't yet see the distinction. This all started coz a pal asked "why do some sites have www as a prefix and some just have HTTP" and I couldn't answer. Is it to do with legacy stuff from the old days before the web? I heard email and newsgroups were net and everything else web but  Yahoo for eg. as a an email facilty is WWW. All very confusing but I do think that maybe my question is one of the group like "what is the dif between flying a helicopter and eating an orange?"
I do not mean to be flippant. I ahven't found a clear explanation anywhere.

[Corrosive]

The reason you only see the www on some sites is that it is completely optional: some servers will allow one of them but most nowadays will accept both forms.

You'll also notice that some sites have other variations on the www. Generally what happens is that the webmaster uses a certain prefix for a certain type of site (www. for websites, pop. for mail servers, ftp. for FTP sites etc). This is merely a standard way of doing things, and many companies/induviduals decide to buck the trend. The BBC's news site has a news. prefix, which is normally associated with newsgroups.

[mark_c]

OK thanks very much. Clearer now. HTTP is a protocol for file transfer. WWW is prefix for an url, part of the domain name. Thanks for all your replies.