What is SEO? Search Engine Optimization Explained
How search engines discover, crawl, index, and rank web pages — and the strategies that help your site appear at the top.
SEO (Search Engine Optimization) is the practice of making your website easier for search engines like Google to find, understand, and rank. When someone searches for a product, service, or question, search engines scan billions of pages and return the most relevant results. SEO is how you make sure your site is one of them. It involves optimizing your content, site structure, performance, and authority so search engines trust and recommend your pages.
How search engines work
- Crawling: Search engine bots discover pages by following links across the web.
- Indexing: Pages are analyzed and stored in a massive database (the index).
- Ranking: Algorithms score pages based on relevance, quality, and authority.
- Results: The highest-scoring pages appear at the top of search results.
The three pillars of SEO
SEO is built on three pillars: Technical SEO (site speed, crawlability, structured data), On-Page SEO (content quality, keywords, meta tags), and Off-Page SEO (backlinks, social signals, brand mentions). All three must work together for strong rankings.
On-page SEO essentials
Technical SEO checklist
Why SEO matters
SEO drives organic (free) traffic to your site. Unlike paid ads, results compound over time — a well-optimized page can rank for months or years. For businesses, SEO is one of the highest-ROI marketing channels available.