Tags

Tags are short keywords or labels attached to digital items to describe content, context, or attributes. They function as descriptive metadata created by users or systems to facilitate discovery, organization, and retrieval. Unlike formal metadata, tags are often informal and may vary in language, granularity, and specificity.

There are two broad approaches to tagging: folksonomies, where users freely assign tags, and controlled vocabularies or taxonomies, where a predefined list dictates permissible terms. Many platforms blend both, offering suggestions or synonyms to improve consistency. Tagging can present issues such as ambiguity, synonyms, or drift as terms change in meaning over time.

Applications include tagging in social media, bookmarking services, photo and video libraries, code repositories, and document collections. Tag clouds, facets, and tag-based search enhance discovery and navigation. Benefits include flexible organization, collaborative curation, and improved search; drawbacks encompass inconsistent tagging, duplication, spam, and the need for governance.

From a data-management perspective, tags are typically modeled as a many-to-many relationship between items and terms. Systems may normalize case, handle pluralization, and support synonyms or polysemy mappings. Best practices favor concise terms, avoidance of duplicates, and periodic review to maintain a usable tag ecosystem. Standards such as Dublin Core keywords or SKOS can inform tagging policies.

In practice, tagging tools appear across platforms: photo sites, social networks, music and video services, and digital libraries. The concept underpins folksonomies, taxonomies, and ontology design, illustrating how user-generated labeling interacts with formal description schemes.