Có thực sự cần thiết để thêm ‘www’ vào URL của trang web trong trình duyệt hiện đại ngay bây giờ không?

In modern web browsers, is there any point in putting ‘www’ in front of a website URL that uses it? When going to ‘www.facebook.com’ or ‘www.cbc.ca’, is there any benefit or difference made by omitting the ‘www’?

It usually doesn’t, but it could.

This has nothing to do with the browser; it has to do with the web-server. The web-server is a computer (or even multiple computers) which receive queries for web-pages and send the appropriate data. A URL includes several parts, one of which is the name or address of the web-server.

Many companies host more than just a web-server, they may also run an FTP-server, a database-server, a mail-server, and so on. These could be hosted from the same machine as the web-server or on different machines.

In the past, it was common to specify the difference via a prefix for consistency. So for example, Acme Industries might buy the domain-name ‘acme.org’, then set up one or more computers to host the different services they have. When you want to use one of the services, you enter the appropriate host name:

Differentiating the service or machine being accessed can also be done through the port, but it requires specifically including it in the name, so it’s not really any better than using prefixes:

It’s becoming less and less necessary to include ‘www’, but it is not universal, and some sites still require it because it helps keep things organized.