Cross Linking

Cross linking was a good way to boost Pagerank in the past. By exchanging links with other websites, called reciprocal links, PageRank could be increased greatly in the past. The search engines caught up and didn’t weigh reciprocal links that heavy as one way links.
After this happened people started cross linking, where links were exchanged via links from a different site a site was linking to. This way a triangular linking structure was accomplished. For search engines it’s harder to discover this scheme, but they are catching up, and cross linking will not be as lucrative in the future.