SEO stands for Search Engine Optimization. It is a process of optimizing websites or web pages to improve their ranking and visibility on search engines, such as Google, Bing, Yahoo, etc. The goal of SEO is to increase organic (non-paid) traffic to a website by making it more relevant and authoritative in the eyes of search engines. SEO involves a range of techniques, including on-page optimization (improving website content, meta tags, and HTML structure), off-page optimization (building backlinks and social media presence), and technical optimization (improving website speed, mobile responsiveness, and security). SEO is an essential part of digital marketing and can help businesses increase their online visibility, attract more leads, and generate more revenue.