Linkjacking occurs when an individual submits content to an aggregation service like Digg.com that contains only links to other sites and no actual content. These sites, which are often called aggregators, collect content from around the Internet. For example, Google News aggregates news headlines from different magazines and newspapers to present news information in one convenient place.
Another example of an aggregator is Digg.com. Digg accepts user submissions to aggregate stories found on the Internet. When submitting a story to Digg, the reader simply clicks a link on the page to vote for the content on Digg. Those with the most votes will be closer to the front page.
So what does all of this have to do with linkjacking or even links in general?Aggregation sites pull content in from other sites. When someone interested in linkjacking a site posts content, the items they submit are nothing more than a list of hyperlinks to sites they own or to sites they wish to promote. This content will be read by the aggregator and displayed, but when a visitor sees the page that has been linkjacked, they will see links that redirect them to other sites with no content. Linkjacking is a way to drive content to a designated site.
Comments in a blog can be linkjacked as well. Any website that receives comments or content from its user community can experience linkjacking. It is not a recommended practice and will likely get content removed from the posting site.
Sites like Digg and Google News have computer programs and staffs of individuals helping to make sure that if linkjacking does occur, it can be corrected quickly. Smaller sites like blogs usually are less susceptible because posting is kept to a select group. Linkjacking can occur in a blog's comments however. To reduce the potential for linkjacking in a blog, a comment spam application which requires the blog administrator to moderate comments is a good idea. Also requiring users to register to post comments can cut down on the amount of comments posted overall, reducing the likelihood further that a blog's comments will be linkjacked.