There are a variety of different types of SEO services, but some of the most common include title tags and meta descriptions; backlinking (including linking to your site from other high-quality websites); on-page optimization (including using keyword-rich content, using effective images and using valid HTML/CSS); and social media engagement (including creating positive content, sharing links & promoting contests). While each service has its own unique benefits and requirements, many of these optimizations generally work together to create a more comprehensive online marketing strategy.