A search engine is an online service that retrieves documents in response to a query. The simplest form of search engine is a list of web pages ranked by the number of times the keyword appears on each page.
Search engines are one of the most important inventions of the digital age. They provide us with information on billions of topics, and they connect us with people all over the world. Most search engines work on a process called "crawling." This is when software crawls through text on web pages to find words or phrases that are relevant to your search term.
Crawling and indexing are both processes involved in search engine optimization. Crawling is the process of a search engine analyzing a site's content and indexing it to make it easily available for a user to find on a search engine's results page.
Search engine crawlers, or web crawlers, are computer programs that search through a site and its links for information. The crawler can look at the content on a page and then index the pages to create an organized list of links. Crawlers can also be programmed to follow links found while looking for content.
Robots.txt is a text file that is placed in the root directory of the website to tell web crawlers what they should or shouldn't crawl. It allows site owners to define which parts of their site should not be indexed, for example, passwords or other sensitive information.