Link building is basically the process of getting links that point to your website pages to increase visibility and ranking in search engines. Link building can be external (i.e., acquiring links from other websites pointing to your pages) or internal (i.e., building links from within the pages on your site).
External link building
When a high-quality and authority website links to your page, it’s a signal to search engines that your website must be of good quality as well. External link building is the practice of acquiring links from these reputable websites in order for your own authority as a website to increase (primarily in search engines’ eyes) as well.
External link building can also help increase referral traffic to your pages, especially if the website linking to your pages get a huge number of visitors or readers regularly. Therefore, avoid “building links” in spammy or shady blogs, but instead seek partnership with high-quality websites that are relevant to your industry.
Internal link building
Building links from within your own website helps in a lot of ways—first, visitors can better navigate your site when you have links guiding them to related pages, and second, internal linking helps Google determine which pages are of higher importance within your site (e.g., if more links are pointing to certain pages than others).
Internal link building can also help with lowering your bounce rate—with internal links located throughout the page, visitors are better encouraged to explore your site further instead of clicking away when they’re done with the current page.
Take care, though, that you don’t get carried away with linking every single part of your content. Only add links when they make sense and are actually relevant—overcrowding your pages with links can only distract your visitors or readers from the current content.
Follow vs nofollow links
In link building, there is a distinction between so-called “follow” (sometimes “dofollow”) and “nofollow” links. These two types of links tell search engine crawlers whether to literally follow a linked site in your page or not.
By default, links are set to follow, which means that when search engines crawl your page, they will follow and crawl these linked pages as well. As mentioned previously, links serve as a signal of a site’s authority or quality—when search engines follow a link from one site to another, the PageRank or the ranking power from the linking site is transferred to the site it’s linking to.
There are some cases, though, where you would need to link to an external site within your content, but not necessarily want to pass that “signal”. This is what nofollow links are for.
Nofollow is an HTML attribute that you add to a link, explicitly telling search engines to not crawl the linked page and not pass any PageRank to it. Nofollow is typically used for paid links or websites that you wouldn’t want Google to associate your site with.