A robots.txt file minimizes the accessibility of any website by the crawlers and search engine robots as well as restricts the site from being indexed. These fully automated bots check and verify whether the robots .txt file exists as the presence of these automated implement prevent the crawlers from accessing certain pages of a site. Any authentic robot follows the directives available in the robots .txt file, but the individual interpretation may vary. But in certain circumstances the robots.txt file is not mandatory as it is ignored by spammers and other trouble makers. In this context, it is prudent to use a password for confidentiality. Different robots interpret robots .txt files differently as all robots are not supported by every directive in the file. Though are all efforts have been taken to create robots.txt files that work for all robots, the search engines, however, do not guarantee the manner in which the files would be interpreted.
A web client should make use of robots.txt file only when their site contains confidential content which they do not want to be indexed by search engines. However, if the web client wants the search engines to index all the web pages of the site then they should not install the robots .txt files. Google may be restricted from “crawling” and indexing the web content of pages blocked by robots .txt file but it can still index URLs if they are visible on other web pages. Under such circumstances, the URL of the page along with the Anchor .txt, that has publicly available information and links to the site, appears in Google search results. It may also appear as a title from Open Directory Project.
While using the robots .txt file one needs to have access to the root of the domain. But if this is not feasible, then accessing the robots Meta tag helps. Web clients, who do not have root access to their server, use Meta tags to block access to the site as it allows them to control access on a page to page basis. To restrict robots from indexing a page on the website, placing a Meta tag into the “head” section of the page helps whenever a “no index” Meta tag appears on that particular page. Google completely drops a page from search results in spite of the presence of links connecting the site to other pages. However, some search engines read the directives differently which often results in the links to the page appearing in their search results.
Search engines are dependent on robots to collect information from the web. To regulate the crawling activities, the Robots Exclusion Protocol is deployed in a file called Robots Text. Websites can explicitly specify the access preference for individual robots. This may result in few search engines dominating the web since they have access to resources that are inaccessible to other search engines.