Link popularity refers to the number of backlinks (incoming links) that point to a given website. In contrast to domain popularity, every backlink is counted separately. For example, in a blog about cars there are 10 different entries that have links to the website of a car dealer. In this case you would count a total of 10 backlinks. Link popularity used to be an important figure for search engines. These days many search engines have switched to focus on domain popularity, which in addition to quantity provides information about the quality of the backlinks. For this reason it is important to get as many high-quality backlinks as possible, since everyone who clicks on a backlink will be directed to your website.