The sesond of ten factors that are considered (by search engine experts) to be key elements of Google’s page rank algorithms. You can read the complete article, ‘Page Rank Factor Secrets‘ by clicking the link.

2. Global Link Popularity of Site – this means the link weight or authority as measured by links from other websites, ranked by link quality and quantity. If your site is important in its niche then other relevant sites will mentions you in their articles and blogs, and seek link exchanges with you. So you need to work on your link exchanges regularly.