meta tag
Metatags are invisible additional information in the header of HTML pages. They are HTML elements that describe the corresponding document in metadata.
They contain structural information about the subject area, the content and the target audience, about search words, the author(s), the date of creation, the language in which the document is written, in them are instructions for robots of search engines whether the web page should be read in or not and whether links should be followed or not.
Metatags can be interpreted by search engines and facilitate search operations on the World Wide Web(WWW). This content information can also be noted by the Web server and document management. Metatags are also used for abusive applications by inserting false keywords into the metatags in order to be better positioned in the results pages( SERP).