Search engine optimization (SEO) is the process of improving the visibility and ranking of a website or webpage on search engine results pages (SERPs). The goal of SEO is to increase the quantity and quality of traffic to a website through organic search results.

Optimizing a website for search engines involves making changes to its design, content, and coding to make it more attractive to search engines. This can include researching and using keywords in the website's content, improving the website's loading speed, and making the website mobile-friendly. The idea is to make the website more easily discoverable and relevant to search engine users.

SEO is an ongoing process, as search engine algorithms and user behavior are constantly changing. It's not a one-time task, it requires consistent and continuous effort to maintain and improve the website's visibility in the search results.

1. On-page SEO: This type of SEO focuses on optimizing the content and structure of a website to make it more search engine friendly. This includes optimizing the title tags, meta descriptions, header tags, and keyword usage within the website's content. On-page SEO also includes optimizing the website's URLs, images, and internal linking structure.
2. Off-page SEO: This type of SEO focuses on building backlinks to a website from other websites. Backlinks are links from other websites that point to your website. The more backlinks a website has, the more authoritative it is considered by search engines. Off-page SEO also includes building a strong social media presence and online reputation.

Both On-page and Off-page SEO are important for the overall performance of a website in the search engine results, and they work together to improve the visibility and ranking of a website.

Additionally, there are some other types of SEO, like Technical SEO, which is focused on improving the technical infrastructure of a website to make it more search engine friendly. Local SEO, which is focused on optimizing a website for local search results, and E-A-T (Expertise, Authoritativeness, Trustworthiness) which is focused on showing your website as a reliable source of information