A spider is an alternative term for a web crawling bot employed by search engines to systematically analyze and rank web pages. The term “spider” is often used to refer to more complex or advanced crawling programs and can be utilized by web developers to gauge the SEO status of a page or an entire site.
Spiders, also known as bots or crawlers, methodically explore the internet to create an index of web pages. The information gathered is stored in databases which are then used by search engines to suggest content based on a user’s search query.
The core function of a spider is to locate web pages, scan them for relevant information and keywords, catalog that information into the database, and retrieve it when a search query seeks similar content.
Website owners can help guide spiders by using a robots.txt file, submitting an XML sitemap, or applying noindex tags to pages they do not wish to appear in search results. Given the limited computing power and server resources, sites are not crawled continuously. It is common for spiders to access a site roughly once every three to four weeks.