SEO stands for Search Engine Optimization. It is a set of practices and strategies aimed at optimizing a website or online content to improve its visibility and ranking on search engine results pages (SERPs). The ultimate goal of SEO is to attract more organic (non-paid) traffic to a website.

Key aspects of SEO include:

1. Keyword Research: Identifying relevant and high-performing keywords that potential users might use to search for information related to your content or business.
2. On-Page SEO: Optimizing individual web pages to improve their search engine rankings. This involves optimizing content, meta tags, headers, images, and ensuring that the website is user-friendly.
3. Off-Page SEO: Building external signals, such as backlinks (links from other websites), social media signals, and other online mentions that can contribute to a website's authority and credibility.
4. Technical SEO: Ensuring that the technical aspects of a website are optimized for search engines. This includes factors like site speed, mobile-friendliness, crawlability, and proper indexing.
5. Content Quality: Creating high-quality, relevant, and valuable content that not only attracts visitors but also encourages them to engage and share the content.
6. User Experience (UX): Ensuring that the website provides a positive and seamless experience for users, including easy navigation and fast loading times.

Search engines, such as Google, use complex algorithms to determine the relevance and authority of web pages. SEO helps websites align with these algorithms, increasing the likelihood of ranking higher in search results, which, in turn, can lead to more visibility and traffic for the site.