Crawling is the automated process by which search engines systematically browse the internet to discover and index new or updated web pages. Specialized programs known as "crawlers" or "spiders" follow links from one page to another, collecting data about each page's content, structure, and metadata. This information is then used to update the search engine's index, ensuring that users receive the most relevant and up-to-date results when they perform a search. Crawling is a foundational step in search engine optimization (SEO) and plays a critical role in how websites are found and ranked online.