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In this article, we'll go over what hyperlinks are and why they matter.

前提: 你该知道 互联网是怎样工作的 ,并且熟悉 网页,网站,网络服务器和搜索引擎间的区别
目标: Learn about links on the web and why they matter.

概述

超链接(Hyperlink),通常简称为链接(link),是网络背后的核心概念。为了解释什么是链接,我们需要回到网络架构的底层。

Back in 1989 Tim Berners-Lee, the Web's inventor, spoke of three pillars on which the Web stands:

  1. URL, an address system that keeps track of Web documents
  2. HTTP, a transport protocol to find documents when given their URLs
  3. HTML, a document format allowing for embedded hyperlinks

As you can see in the three pillars, everything on the Web revolves around documents and how to access them. The Web's original purpose was to provide an easy way to reach, read, and navigate through text documents. Since then, the Web has evolved to provide access to images, videos, and binary data, but these improvements have hardly changed the three pillars.

Before the Web, it was quite hard to access documents and move from one to another. Being human-readable, URLs already made things quite a bit easier, but it's hard to type a long URL whenever you want to access a document. This is where hyperlinks revolutionized everything. Links can correlate any text string with a URL, such that the user can instantly reach the target document just by activating the link.

By default blue and underlined, links stand out from the surrounding text. Tap or click a link to activate it, or if you use a keyboard, press Tab until the link is in focus and hit Enter.

Example of a basic display and effect of a link in a web page

Links are the breakthrough that made the Web so useful and successful. In the rest of this article, we discuss the various types of links and their importance to modern Web design.

深入探索

As we said, a link is a text string tied to a URL, and we use links to allow easy jumping from one document to another. That said, there are some nuances worth considering:

链接的类型

内链
A link between two webpages that both belong to your website. Without internal links, there's no such thing as a website (unless, of course, it's a one-page website).
外链
A link from your webpage to someone else's webpage. Without external links, there is no Web, since the Web is a network of webpages. Use external links to provide information besides the content that you yourself maintain.
Incoming links
A link from someone else's webpage to your site. It's just the opposite of an external link. Note that you don't have to link back when someone links to your site.

When you're building a website, focus on internal links, since those make your site usable. Find a good balance between too many links and too few. We'll talk about designing website navigation in another article, but as a rule, whenever you add a new webpage, make sure at least one of your other pages links to that new page. On the other hand, if your site has more than about ten pages, it's counter-productive to link to every page from every other page.

When you're starting out, you don't have to worry about external and incoming links as much, but they are very important if you want search engines to find your site. (See below for more details.)

大多数链接将两个网页相连。而锚将一个文档中的两个段落相连。When you follow a link pointing to an anchor, your browser jumps to another part of the current document instead of loading a new document. However, you make and use anchors the same way as other links.

Example of a basic display and effect of an anchor in a web page

链接和搜索引擎

Links matter both to your users and to search engines. Every time search engines crawl a webpage, they index the website by following the links available on the webpage. Search engines not only follow links to discover the various pages of the website, but also use the link's visible text to determine which search queries are appropriate for reaching the target webpage.

So links influence how readily a search engine will link to your site. The trouble is, it's hard to measure search engines' activity. Companies naturally want their sites to rank highly in search results, and all the resulting study makes at least a few things clear:

  • A link's visible text influences which search queries will find a given URL.
  • The more incoming links a webpage can boast of, the higher it ranks in search results.
  • External links influence the search ranking both of source and target webpages, but just how much is not clear.

SEO (search engine optimization) is the study of how to make websites rank highly in search results. Improving a website's use of links is one helpful SEO technique.

下一步

So now of course you'll want to set up some webpages with links!

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