A backlink is an incoming link from an external website to specific webpage. For example, if you publish a webpage and 20 other websites link to it, your webpage has 20 backlinks. Links to the page from within your own website are not included in the backlink total.
Web developers benefit from backlinks (or "inlinks") in two different ways — direct traffic and search result placement. As more links to a specific webpage are published on external sites, there is greater potential for traffic to be generated from other websites. This is called direct traffic. By increasing direct traffic, a website can gradually grow its presence on the Web and generate a steady stream of visitors from other websites.
While direct traffic is helpful, most websites generate the majority of their traffic through search engines. Since search engines use backlinks as an important part of the their algorithms for search result placement, external links are important for good search ranking. Therefore, generating backlinks has become common practice for search engine optimization, or SEO. The more backlinks a webpage has, the better the chance that the page will rank highly in search results for relevant keywords. If a website has many pages that have backlinks, the overall number of incoming links may help increase the ranking of all pages within the website. While most backlinks point to a website's home page, incoming links to other pages within the website are beneficial as well.