|Tagging refers to the process by which users assign a Tag (which is an index term assigned to a piece of information) to a resource in the online environment, such as an Internet bookmark, digital image, or computer file.
Purpose of tagging:
Tags are generally chosen informally and personally by the item's creator or by its viewer, depending on the system. Tagging is carried out to perform functions such as aiding in classification, marking ownership, noting boundaries, and indicating online identity. Tagging has emerged (1) as a method for filtering and promoting content or (2) to help describe an item and allow it to be found again by browsing or searching. See also: Folksonomy