Tracking metrics for link building depends on your goals and tools, but some of the most important ones are the number of backlinks and referring domains, link quality, diversity, velocity, and attribution. The number of backlinks and referring domains refer to the total number of links pointing to your website or a specific page from unique domains. Link quality measures the relevance, authority, and trustworthiness of the links and the domains they come from. Link diversity measures the variety of the links and the domains they come from in terms of type, location, industry, and topic. Link velocity is the rate at which you acquire or lose links over time, while link attribution is the attribution of the links to the source and method of acquisition such as outreach, guest posting, content marketing, or social media.