You may be wondering what a backlink is, and why backlinks are important. Backlinks have become so important to Search Engine Optimization, that they have become some of the main building blocks to good SEO.
Backlinks are links that are directed toward your website and are also knows as inbound links. The number of backlinks is an indication of the importance of that website. Backlinks are important because some search engines, especially Google, will give more credit to websites that have a good number of quality backlinks and consider those websites more relevant than others in their search query results pages.
When search engines calculate the relevance of a site to a keyword, they consider the number of "quality" inbound links to that site. It is not enough to just get inbound links, it is the quality of the inbound link that matters.
A search engine considers the content of the sites to determine the quality of a link. When inbound links to your site come from other sites, and those sites have content related to your site, these inbound links are considered more relevant to your site. If inbound links are found on sites with unrelated content they are considered less relevant. The higher the relevance of inbound links the greater their quality.
If you have a website about how to sell motor cars, and received a backlink from another website about cars, then that would be more relevant in a search engine's assessment than a link from a site about gardening. The more relevant the site is that is linking back to your website, the better the quality of the backlink.
Another reason to achieve quality backlinks is to entice visitors to come to your website. You can't build a website and then expect people to find your website without pointing the way. You will probably have to get the word out about your site.
Building quality backlinks is extremely important to Search Engine Optimization, and because of their importance, it should be very high in your priorities list in your SEO efforts.