What is the main usage of search engine spiders?

[Katherine Parker]

What is the main usage of search engine spiders?

Search engine spiders, sometimes called crawlers, are used by Internet search engines to collect information about Web sites and individual Web pages. The search engines need information from all the sites and pages; otherwise they wouldn't know what pages to display in response to a search query or with what priority.

Search engine spiders crawl through the Internet and create queues of Web sites to investigate further. As a specific Web site gets covered by a spider, the spider reads through all the text, hyperlinks, meta tags (meta tags are specifically formatted key words inserted into the Web page in a way designed for the spider to find and use) and code. Using this information, the spider provides a profile to the search engine. The spider then gathers additional information by following the hyperlinks on the Web page, which gives it a better collection of data about those pages. This is the reason that having links on your Web page – and, even better, other Web pages linking to yours -- is so useful in getting your Web site found by the search engines.

[Sheldon Mooze]

What is the main usage of search engine spiders?

What is Web Crawling?

Web crawling A.K.A. web spidering means on the web, we can only "crawl" or browse web pages in a methodical and automated manner.
Web crawling is used to create a copy of all the visited pages for later processing.
Web crawling is typically used for the purpose of Web indexing. Its all about browsing the web in an automated manner for the purpose of content indexing.
Search engines like Google, Bing, and Yahoo use crawling to properly index downloaded pages so that users can find them faster and more efficiently when they are searching.
A bot A.K.A. crawler or spider is a program or automated script which crawls a website, it goes through every page and every link, until the last line of the website, looking for ANY information.
GoogleBot, BingBot, Yahoo Slurp, DuckDuckBot, Baiduspider, YandexBot, SogouSpider are few well-known Search Engine web crawlers.
Web crawlers can be used to gather any information from Web pages, such as harvesting e-mail addresses (usually for spam).
Example: If we need all the email address available on a website then we have to crawl to that website and we should search in the text content of every web page with email regular expression to find all email addresses.
How Does Search Engine Work?

There are 3 main components:

Crawling – Following links to discover the most important pages on the web.
Indexing – Storing information about all the retrieved pages for later retrieval.
Ranking – Determining what each page is about, and how it should rank for relevant queries.
Thank you for the question!!

[firstdigiadd]

 Spiders understand the way pages and sites are constructed and also, the way they are tied to other sites or internal pages. All of this information is used to help search engines like Google, Yahoo, and Bing determine where a page should be listed in the SERP (search engine results page)

[cristine410]

The spiders are the bot of search engines, that crawl on www means the world wide web. their work is to check each website or web page getting registered on www, they crawl on www, and whenever a website or webpage gets registered there, they go to the site take a snapshot of the webpage and feed it to the google directory to index the site, so that after googling filter the site according to site niche, content, nature google fetch the site in the suitable category and whenever a user searches a query, google revert it to the best suitable website as result.

[Wiley Harding]

Its primary job is to discover and crawl URLs, fetch resources, parse pages and provide data for indexing. Rankings come later through completely different systems.