A web crawler (also known as a web spider or a web robot) is a computer program that browses the World Wide Web in an automated manner for the purpose of indexing web content or gathering web data.
Web crawlers are used to index webpages for search engine databases and to retrieve data for a wide variety of applications, such as price comparison, website change detection, web data extraction and website information gathering. By using a web crawler, a webmaster can ensure that their website is indexed quickly and accurately, thus making it easier for customers to find the information they are looking for.
Web crawlers typically start with a list of URLs to crawl, and can be configured to follow links generated within the webpage. The crawler follows each link and continues to do so until it has indexed the entire website. Additionally, some web crawlers are programmed to track webpages that have changed since their last visit.
The web crawler is an integral part of the web search engine. They are used to ingest and store the data gathered from websites, so that the search engine can provide accurate and up to date results of a web search.
In addition to web search engines, web crawlers may be used by digital marketers to improve customer experience on a website, and by data scientists to process web data for knowledge discovery.
Web crawlers can be programmed to comply with web robots exclusion standard (also known as the robots.txt protocol). This enables website owners to restrict the crawling of certain sections of their website or to disallow certain crawlers entirely.
The use of web crawlers is subject to the existing laws regarding privacy, copyright, and the responsibility of website owners.
