Crawling and indexing are the foundational processes by which search engines discover and store web content—crawling is the discovery phase through link-following, while indexing is the storage and organization of discovered content for retrieval.
Crawling is the process where search engine bots (crawlers or spiders) follow links from known pages to discover new content. Crawlers have limited resources—they prioritize crawling based on page importance, update frequency, and site authority. Once a page is crawled, the search engine analyzes its content and stores it in the index—a massive database of words, concepts, and signals. Indexing involves parsing content, identifying key topics, and understanding relationships between concepts. Pages that are not indexed cannot appear in search results, making crawlability and indexability essential for SEO success.