Www...........

[Stav]

Why do some internet sites have www. at the beginning, but some not, (eg uk.imdb.com)?

[lisaj]

Bear with me, but to understand this, you really have to understand DNS.

DNS, or the Domain Name System, is the name given to the tables that correlate IP addresses (which computers use to communicate) and the friendly names (which humans use). Now, the names are entirely hierarchical - that is to say there is a domain called ".com" - and at any point there can be a record pointing to an IP address, such as "www.com". Of course, rather than being a single record, this could be a 'subdomain', which in turn would have further records under it, so rather than ".com", we could have ".uk", which in turn would have ".co" under it. Now we could just have a record here called "answerbank" that would point to a web server, and if so, the name of this website would be "http://answerbank.co.uk" - however... because of the different types of services that computers provide, it became customary to call a web server "www", and give it it's own record, with "answerbank" again being a subdomain - hence the address being "www.answerbank.co.uk". Likewise a machine that served FTP might be called "ftp.answerbank.co.uk". Of course these needn't be different machines - the two records could simply point to the same IP address.

[Pinotage]

To understand the answer you don't need to know anything about DNS.

 

What you are looking at is a website. The world wide web uses the Internet to connect the various sites together. (If the web is a TV programme, then the internet is the transmitter & aerial & wires etc.)

 

The internet was around for decades before the web came along. When the first faltering steps of the web were taken, they used www at the start of the address to tell everyone it was a website.

 

Its a convention - its just a name - and its not necessary, but if a site starts www then printing the adddress www.something.com in a paper or advert is understood by everyone, if it doesn;t have www then you often need toput http://anything.com tel tell people its a web address.

[lisaj]

Pino: One would argue that your answer is derived from your own knowledge of DNS, and that your answer in itself is the same as mine, but without the detail (which can be used to derive the answers to further questions on a similar topic). Either way, I think the question has been fully answered between the two of us.