Web crawler facts for kids
A web crawler (also called a spider or bot) is a special computer program that automatically explores the internet. Think of it like a robot that visits web pages all by itself. Its main job is to fetch (or download) the information from these pages. After collecting the content, the program looks at it closely. For example, it might figure out what the page is about so that it can be found when someone searches for certain words. Big Search engines like Google use web crawlers all the time to build their huge indexes of websites.
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What Do Web Crawlers Do?
Web crawlers are super important for how we find information online. They constantly travel across the internet, following links from one web page to another. This helps them discover new pages and updates to old ones. Without these digital explorers, search engines wouldn't know what's out there, and it would be much harder for you to find what you're looking for!
How Do Spiders "Crawl" the Web?
Imagine a spider spinning a web. A web crawler works in a similar way, but instead of silk, it uses links!
- Starting Point: A crawler begins with a list of web addresses (URLs) to visit. These are like its starting points.
- Following Links: When it visits a page, it reads the content and finds all the links on that page.
- Adding to List: It then adds these new links to its list of pages to visit later.
- Repeating: This process repeats over and over, allowing the crawler to explore billions of pages.
Why Are They Called Spiders?
They are called "spiders" because they crawl through the "web" of the internet, much like a spider crawls through its own web. They also create a network of connections between pages, just like a spider's web connects different points.
Why Are Web Crawlers Important?
Web crawlers are the backbone of search engines. They help search engines do two main things:
- Discover New Content: They find new websites and pages that have just been created.
- Update Old Content: They check existing pages for changes or new information.
This constant updating means that when you search for something, the results are usually fresh and accurate.
Indexing Information
After a web crawler fetches a page, it sends the information back to the search engine. The search engine then "indexes" this information.
- What is Indexing? Indexing is like creating a giant library catalog for the internet. The search engine reads the page, understands what it's about, and stores it in its massive database.
- Keywords: It notes down important words (keywords) from the page. So, if a page is about "space exploration," the search engine remembers that.
- Faster Searches: When you type a query into a search engine, it doesn't search the entire internet in that moment. Instead, it quickly looks through its index to find the most relevant pages, which is why results appear so fast!
Rules for Web Crawlers
Website owners can tell web crawlers which parts of their site they can and cannot visit. They do this using a special file called `robots.txt`.
- Privacy: This file helps website owners protect certain information or prevent crawlers from overloading their servers.
- Good Behavior: Most good web crawlers respect these rules and only visit the parts of a website they are allowed to.
Images for kids
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This chart shows how "fresh" (new) and "old" (age) information is for a web crawler.
See also
In Spanish: Araña web para niños
