Backlinks are links that point to your site. The more links you have the more important search engines will class your site. Backlinks are an integral part of any SEO campaign and are seen by some as one of the hardest areas of SEO.
When gaining Backlinks the aim is to generate links from trusted and relevant site. There are various method to generate links to the site, these methods have changed over the past few number of years. Old methods include directory submission, blog commenting, paid links, article reviews, guest articles to name a few methods.
However due to the overuse of these methods Google cracked down on sites with backlink profiles made of links gained from the methods named above.
A sustainable method of building links is to create a useful sites / service which intern with generate links. There are various methods to this format from producing useful content, offering a great service or participating in the online community.