Tag (metadata)
Computer based search algorithms made the use of such keywords a rapid way of exploring records.
[2] These sites allow users to create and manage labels (or "tags") that categorize content using simple keywords.
[3]: 142 This definition of "top down" and "bottom up" should not be confused with the distinction between a single hierarchical tree structure (in which there is one correct way to classify each item) versus multiple non-hierarchical sets (in which there are multiple ways to classify an item); the structure of both top-down and bottom-up taxonomies may be either hierarchical, non-hierarchical, or a combination of both.
[3]: 142–143 Some researchers and applications have experimented with combining hierarchical and non-hierarchical tagging to aid in information retrieval.
Online databases and early websites deployed keyword tags as a way for publishers to help users find content.
In 1997, the collaborative portal "A Description of the Equator and Some ØtherLands" produced by documenta X, Germany, used the folksonomic term Tag for its co-authors and guest authors on its Upload page.
[18] In "The Equator" the term Tag for user-input was described as an abstract literal or keyword to aid the user.
[20] The success of Flickr and the influence of Delicious popularized the concept,[21] and other social software websites—such as YouTube, Technorati, and Last.fm—also implemented tagging.
All connections between posts are automatically tracked and updated by the blog software; there is no need to relocate the page within a complex hierarchy of categories.
[26] In later iterations of the Mac operating system ever since OS X 10.9 was released in 2013, users could assign multiple arbitrary tags as extended file attributes to any file or folder,[27] and before that time the open-source OpenMeta standard provided similar tagging functionality for Mac OS X.
[30] Cross-platform file tagging standards include Extensible Metadata Platform (XMP), an ISO standard for embedding metadata into popular image, video and document file formats, such as JPEG and PDF, without breaking their readability by applications that do not support XMP.
Exif is a standard that specifies the image and audio file formats used by digital cameras, including some metadata tags.
[34] Search engines can then index them to make relevant materials related to the event searchable in a uniform way.
A researcher may work with a large collection of items (e.g. press quotes, a bibliography, images) in digital form.
[40] Specialized metadata for geographical identification is known as geotagging; machine tags are also used for other purposes, such as identifying photos taken at a specific event or naming species using binomial nomenclature.
A knowledge tag is a type of meta-information that describes or defines some aspect of a piece of information (such as a document, digital image, database table, or web page).
[42] Knowledge tags are more than traditional non-hierarchical keywords or terms; they are a type of metadata that captures knowledge in the form of descriptions, categorizations, classifications, semantics, comments, notes, annotations, hyperdata, hyperlinks, or references that are collected in tag profiles (a kind of ontology).
[42] These tag profiles reference an information resource that resides in a distributed, and often heterogeneous, storage repository.
[2] Hierarchical classification systems can be slow to change, and are rooted in the culture and era that created them; in contrast, the flexibility of tagging allows users to classify their collections of items in the ways that they find useful, but the personalized variety of terms can present challenges when searching and browsing.
Despite the apparent lack of control, research has shown that a simple form of shared vocabulary emerges in social bookmarking systems.
