Metadata is “data about data”. This means it's information about somthing, that makes it easier to find that particular information ressource.

Companies use metadata to manage large amount of data. The data can usually be read and analyzed automatically. The file name and the permissions on a file are metadata of a file.

Metadata in SEO are the meta tags that are entered in the head area of a page and help search engines indexing it correctly.

Some metadata is particularly important in SEO: description, indexing, title.