Why internal linking is important for website?

we can use a link from a popular, evergreen, post which attracts regular traffic to promote the latest ClickZ Live event, or a piece of paid content we’d like to raise awareness of.

There are other reasons:

• It provides your audience with further reading options. For example, if you are writing about a new product or service from Twitter, and we’ve written a great post on Twitter in the past, link to it. It provides context for the reader and promotes older content.
• It helps to improve your ranking for certain keywords. For example, if we want a page to rank for ‘search marketing statistics’ and we have a page containing these, then we can point people the page using the relevant anchor text. This sends a clear signal to Google that this page is relevant to search users typing in that phrase.
• It can help you to promote events and other paid services. If we’re talking about link-buildng and we have a great speaker on covering that topic at an upcoming event, that’s an opportunity to promote them.
• It helps Google to crawl the site. Internal links in articles, as well as in category and tag pages, help Google to index pages more efficiently.