An inbound link is also known as a backlink and refers to links pointing to your web page that originate from an external source such as a web page from another website or a blog.
Part of comprehensive search engine optimization is to acquire inbound links from relevant, quality sources to help enhance the importance of your web pages in the “eyes” of the search engines. Links that point to your web pages from recognized, high quality sources like a news site, popular blogs on relevant topics, professional organizations, newsletters, and other such websites, let the search engines know that users regard your information as relevant and valuable.
Google use the PageRank™ algorithm to assess the “popularity” of a web page for a particular search term. The higher the PageRank™, the more popular a web page is deemed and the more likely it is to be ranked in the top listing positions of the search engine results pages for the specified term searched.
It is important to understand that acquiring inbound links from questionable or irrelevant sources, such link farms, which are websites that offer no value whatsoever to the end user but are simply web pages filled with unrelated, aggregated links, can be detrimental to your search engine optimization goals. Such Black Hat seo techniques may get your web pages permanently banned from the search engines.
The goal of search engine optimization is always to serve the end-user by providing quality inbound links that lead to relevant, helpful information.