A Web Crawler is an integral part of search engines and web directories. It systematically browses the World Wide Web to index web pages and update web content.
How a Web Crawler Works
A Web Crawler starts with a list of URLs to visit, known as the seeds. As the crawler visits these URLs, it identifies all the hyperlinks in the page and adds them to the list of URLs to visit. This process continues automatically until the Web Crawler has visited every page or a certain limit is reached.
- Seeds: The starting points for the crawl, usually the homepage of a website.
- Hyperlinks: The crawler identifies these in each page and adds them to the list of pages to visit.
Blocking a Web Crawler
Webmasters can control which pages on their site are crawled by using a robots.txt file. This is a text file that instructs web robots how to crawl pages on their website.
- Robots.txt: A file that can be used to instruct web robots how to crawl pages.
Conclusion
Understanding how a Web Crawler works is essential for anyone involved in SEO or running a web directory. By knowing how to control the crawl using a robots.txt file, webmasters can ensure that their most important pages are always indexed.