How does Google discover pages and links?

Google discovers pages and links primarily through web crawlers, also known as spiders or bots. These automated programs systematically browse the internet, following links from known pages to discover new ones. When a crawler finds a new page, it adds it to Google's index, making it discoverable in search results. Robots.txt is a directive file that tells crawlers which parts of a site not to crawl, but it doesn't instruct them on how to discover pages initially. Quality Raters are human reviewers who assess the quality of search results and websites, but they do not discover pages or links themselves; they evaluate content that has already been discovered and indexed.