SEO stands for search engine optimization. The goal of SEO is to help websites rank higher in search engine results pages by optimizing content, code, and backlinks. There are two main types of SEO: on-page optimization, which involves edits to website content and code; and off-page optimization, which focuses on building backlinks through activities done externally from the website like social media sharing, guest blogging, and directory submissions. Effective SEO requires an understanding of how search engines work and involves both on-page and off-page techniques applied regularly over the long term.