Searching for “what is a crawler” or “how does Google search work” yields technical or vague answers. Because there are multiple ways to explain these concepts. We need different perspectives and terminology to understand crawlers and how they work. To explain what a crawler is and how it works, we must examine its many types and functions. Each search engine crawler has its own purpose. They all crawl websites to index their content for future searches.
What is a web crawler?
Web crawlers automatically “crawl” into websites and webpages across the internet. Most crawlers are run by businesses or universities, not search engines. Website diagnostics, search engine indexing, and security auditing use crawlers. Crawlers build search engine indexes most often. This is why many people associate one type of crawler with “search engine”. Crawlers are software robots that act like robots.
Google Web Crawlers
Google Web Crawlers find new websites and map the internet. These crawlers also re-crawl discovered websites to update their data. Google’s “eyes and ears” are crawlers. Google’s first “tools” for finding and ranking content are them. Googlebot finds and adds new content to its databases. Googlebot re-indexes web content. Refreshing websites is crawling.
As mentioned, crawlers have different specialties. Google uses these popular spiders and crawlers. Googlebot: Google’s largest spider. Googlebot maps the internet and finds new websites. Googlebot-news crawls news websites to ensure Google is the first to “hear” breaking news. – Googlebot-video: This bot crawls sites to find and index videos for YouTube. Googlebot-image crawls images to find the latest and greatest. Googlebot-core: The main Googlebot re-crawls websites to keep Google’s search engine up to date. Googlebot-pdf: This bot indexes PDF files for the PDF search engine.
Google’s search engine starts with web crawlers. They find new websites and map the internet. Googlebot re-crawls websites to update their data. Crawlers have different specialties. Every website has a crawler, from image crawlers to news crawlers. Crawlers map websites by entering them. Exploring a building is similar: You could go left, right, up, or down, or through a tunnel instead of around a lake. You could go backwards or try a new path. The crawler explores a website and doubles back to find all the pages. The crawler searches the website, turning left and right, up and down, to find everything on the list. Complex process.
by @MarkPavelich CEO The Mark Consulting & Marketing