A web crawler is a computer program that scans the Internet (also www or world wide web) and inspects web pages. Social Media Marketing Solution provide some names of web crawlers:

· Spider (because they are figuratively walking the world-wide web),

· Robot (because the machine works automatically)

· Search bot (because the robot searches web pages)

Search engines use Web crawlers to automatically analyze pages and include them in their index. Analyzing a page is called crawling (because the little spiders crawl from one URL to another over the big wide web).

Is a web crawler a search engine?

In 1993, Matthew Gray at MIT created the World Wide Web Wanderer, the first Web crawler to measure the size of the Internet. This was based on the programming language Perl.

The first publicly available search engine with full-text index was developed in 1994 by student in his spare time.

The term Web Crawler comes from its name WebCrawler for a program that searches the Internet.

Today there are many search engines and many different web crawlers. Search engines need Web crawlers to search pages.

How does a web crawler work?

A Web crawler is software based on the client-server model. That is, it is not a desktop application, but Web crawlers, as when browsing through the browser, via links from one website to another.

Therefore, a good link building is important for search engines and SEO.

At the beginning of the process, one or more URLs are entered from which the Web crawlers start. The new links are added to the list of known URLs. This process is programmed as an algorithm.

In an algorithm Social Media Marketing Solution explain that the calculation process is specified, which is repeated according to a specific scheme. Ada Lovelace has recorded the first computer algorithm. After her the programming language Ada was named.

Can a Web crawler search the entire Internet?

Theoretically, web crawlers can search all linked pages. Some search engine operators such. However, Google, Yahoo and Bing have agreed on the 1994 Robots Exclusion standard protocol to control the behavior of Web crawlers on websites.

In this case, the Web crawlers must first look in the root directory of a domain, the root directory, for the file https://www.domain-example.com/ robots.txt . Here, the web crawlers read whether they are allowed to follow the links on the website and for which crawler that applies.

However, access by malicious software cannot be prevented. In addition, everyone can see which pages you want to block for Web Crawler.

What do you have to keep in mind when looking for web crawler search engine optimization?

For a web page to appear in search results, it must first be included in the search engine's search index. SEO experts ensure that the websites are optimized for the web crawlers of the search engines.

Sometimes it makes sense to lock individual pages for specific web crawlers. This can be adjusted via the meta tags of the page.

How to program web crawlers?

Of course you can write the software for your own web crawler yourself. There are instructions and tutorials provided by Social Media Marketing Solution for different programming languages.

Here are some examples:

· Programming the search engine, yourself with PHP

· simple web crawler in C #

· Web Crawler in Python with less than 50 lines of code

· simple web crawler in Java