Stands for "Domain Name System." The primary purpose of DNS is to keep Web surfers sane. Without DNS, we'd have to remember the IP address of every site we wanted to visit, as opposed to just the name. Now, I have some computer science friends who might prefer this, but for normal people, names are much easier to remember. The reason for the Domain Name System is that web sites are acutally located by their IP addresses. So, when you type in "http://www.adobe.com", the computer doesn't immediately know that it should look for Adobe's web site. Instead, it sends a request to the nearest DNS server, which matches an IP address to the domain name and then connects you to the server with that IP number. And we just take it for granted.
Meaning of DNS in English
English glossary of computer and Internet terms. Английский глоссарий компьютерных и Интернет терминов. 2012