Why don't some websites add www in front of them?

First we need to understand, what is www? When everyone habitually enters "www. ..." when visiting a website, have you ever thought about what exactly www is?

　 Speaking of this, I remembered an interesting thing. Not long ago, when I was revising a website (let’s call it http://abc.com), I created a test URL using http://ww.abc.com and sent the test address to them. Look, someone actually asked me: "Did you make a typo? Where are the two URLs starting with www?" I was immediately embarrassed and asked: "Don't you think http://ww.abc.com, http:/ Are /www.abc.com and test.abc.com actually the same thing?" The other party replied: "test.abc.com is a second-level domain name, and http://www.abc.com is a first-level domain name." I got cold after hearing this.

Regarding what is a first-level domain name and what is a second-level domain name, Michael F Liu helped us explain very clearly:

First of all, you have to understand some principles of domain names. Domain names are hierarchical. From right to left, domain names go from high level to low level. For example, the .cn domain name in our country is the highest level top-level domain name, and the domain name http://abc.cn is a second-level domain name. If it is a domain name in the form of www.abc.cn, it is actually a third-level domain name.

So why are the most common domain names on the Internet now in the form of www.abc.cn?

　 Speaking of which, this is actually a problem left over from history. In the early days of the Internet, only large companies had access to the Internet. The servers of large companies were of course relatively busy. Email, files, FTP, and of course HTTP were all needed to provide multiple services. One server was definitely not enough. So they handed over different tasks to different servers for processing. In order to distinguish them, they used different subdomain names, which is what we see now: www.abc.cn, ftp.abc.cn, mail.abc. The subdomain name form of cn, gopher.abc.cn, etc.

　Times are developing and technology is advancing. Tasks that originally required multiple servers can now be distributed to multiple servers without having to use subdomain names to distinguish them. For example, Google has countless servers supporting the operation of the domain name http://google.com. Now we continue to use subdomain names purely for the convenience of users.

　So, what is www?

Don’t laugh at me. Many people who started using computers to access the Internet after 2000 have probably never been exposed to some ancient terms, such as the "World Wide Web". Anyone who uses the Internet knows the important role of "WWW"? To enter a URL, you must first type these three letters. These three letters are the abbreviation of the English "World Wide Web". "WWW" has been translated as "Global Network", "Global Information Network", "Hypermedia Global Information Network", etc. in my country, and was finally translated as "World Wide Web" by the National Committee for Approval of Scientific and Technical Terms. That was a long time ago. At that time, our Internet was still very immature, and different services required different tools to complete. Unlike now, basically all services can be completed through the browser.

At that time, the main services provided by the Internet were World Wide Web (WWW), file transfer (FTP), email (E-mail), remote login (Telnet), etc. To put it bluntly, the www (World Wide Web) at that time meant that this was a web service that you needed to access using a browser, rather than a bbs that you needed to access using telnet, or a file transfer service that you accessed with the ftp tool. So at that time, www should be used in front of the domain name of the website homepage.

The definition of www back then was:

WWW is built on the client/server model. WWW is based on Hyper Markup Language (HTML) and Hyper Text Transfer Protocol (HTTP). An information browsing system that can provide a consistent user interface for Internet services. The WWW server uses hypertext links to link information pages. These information pages can be placed on the same host or on hosts in different geographical locations; this link is maintained by a Uniform Resource Locator (URL), and the WWW client The terminal software (i.e. WWW browser) is responsible for information display and sending requests to the server.

The world wide web is a collection of countless network sites and web pages, which together form the main part of the Internet (the Internet also includes email, Usenet, and newsgroups). It is actually a collection of multimedia connected by hyperlinks. What we usually watch online through a web browser is the content of the World Wide Web.

Our Internet has created the new world of www (World Wide Web) through links (http). Because of links, no matter how small a website is, it is not an isolated island; no matter how large a website is, it is not as big as the entire Web that is linked to each other. The cross-website link between two Web pages makes the entire Web become a whole and come to life. Links have become a unique etiquette on the Web. It doesn't matter where a piece of text or a picture exists. What matters is that it exists and anyone can give it a link. It can also be said that the emergence of links has made the Web a public domain.

However, in China, our network is filled with an SLW (Self Limited Web) atmosphere. Sina, Sohu, NetEase, and Baidu blogs still cannot be successfully subscribed through Rss readers. Countless pictures on the Internet that need to be quoted are protected from hotlinking. Displayed as a big logo, countless people take the trouble to copy the same content from one website to another every day, close the service at will, change the content link address, delete the content at will, make the original link invalid, and there is no such thing at all The great wall of existence...

Under such an environment, we need to remind everyone all the time that the reason why your "homepage" domain name is not http://index.abc.com or http://web.abc. com instead of http://page.abc.com but use www.abc.com. That’s because what you are creating is a World Wide Web.

　www is very broad, it requires its users to be broad-minded.