Tagging SystemsMustafa Kilavuz

TagsA tag is a keyword added to an

internet resource (web page, image, video) by users without relying on a controlled vocabulary.

Helps to improve search, spam detection, reputation systems, personal organization and metadata

UsageSocial bookmarking

◦Personal bookmarks◦Allows users to store and retrieve

resourcesSocial tagging systems

◦Shared tags for particular resources◦Each tag is a link to additional

resources tagged the same way by other users

◦Folksonomy: popular tags

Examples of Tagging Systems Flickr: A photo sharing system allowing users to store

and tag their personal photos, as well as maintain a network of contacts and tag others photos.

Del.icio.us: A “social bookmarking site,” allowing users to save and tag web pages and resources.

CiteULike: A site allowing users to tag citations and references, e.g. academic papers or books.

Youtube: A video sharing system allowing users to upload video content and describe it with tags.

ESP Game: An internet game of tagging where users are randomly paired with each other, and try to guess tags the other would use when presented with a random photo.

Last.fm: A music information database allowing members to tag artists, albums, and songs

A model

Vocabulary ProblemDifferent users use different terms to describe

the same thingsPolysemy: A single word has multiple meaningsSynonymy: Different words have the same

meaningAbstraction: Tagging a resource in different levels

of abstraction◦ Animal, cat, Persian cat, Felis silvestris catus longhair

PersianDifferent languagesMissing context: Tags that could not be related

with the images by others◦ Holiday, me, friends, a person’s name

Taxonomy of Tagging SystemsSystem design and attributes

◦How the characteristics of a tagging system effects the content, the tags and the usage

User incentives◦How user incentives and motivations

effect the content, the tags and the usage

System Design and Attributes Tagging rights: A tag can be added or removed by the

creator of the resource, a restricted group or everyone Tagging support: The mechanism of a tag entry

◦ Blind tagging: a tagging user cannot see tags added by others to the same resource

◦ Viewable tagging: all tags are visible◦ Suggestive tagging: the system suggests the user possible tags

Aggregation: Systems allow duplicate tagging (bag-model) or prevent (set-model)

Type of object: web pages, images, videos, songs Source of Material: Resources can be supplied by the

system or the users, or anything on the web can be tagged Resource connectivity: links, groups etc. connecting

resources other than tags Social connectivity: The connection between the users may

result localized folksonomies.

User IncentivesFuture retrieval: To mark items for personal retrieval

of either the individual resource or a collection (playlists)

Contribution and sharing: To add to conceptual clusters for the value of either known or unknown audiences

Attract attention: to attract other users to look at their resources (common tags, spam tags)

Play and competition: to produce tags based on an internal or external set of rules

Self presentation: to write a user’s own identity lo leave a mark

Opinion expression: to convey value judgments that they wish to share with others

Case Study: Flickr Flickr is a photo-sharing site that considers tags as a

core element to the sharing, retrieval, navigation and discovery of user-contributed images.

It allows users to upload their photos and share with the public.

People can create networks, join groups, send messages, comment, tag, choose favorite, explore etc.

It contains user-contributed resources instead of global resources.

It allows self-tagging (or permission-based) instead of free-for-all tagging.

The tags are aggregated in sets instead of bags. It affords blind-tagging instead of suggested-tagging This system design motivates people to tag.

Tag UsageThe tag usage is not mandatory

in Flickr.User can tag their friends’

photos. But within 58 million tag observed, the overwhelming majority are owner tags.

Most people has very few distinct tags while a small group has extremely large sets of tags.

Tag vocabulary size across the set of users

Usefulness and importance of tagsThe number of uploaded photosThe count of user’s distinct tagsThe number of contacts

designated by the userA linear relation

between the photos and the

tags

Might suggest that tagging is

related to social activity

to some degree

Flickr usage correlation

Growth of distinct tags10 users are randomly chosen

◦Frequent uploaders ( > 100 photos)◦Frequent taggers ( > 100 tags)

The number of distinct tags are observed as the number of photos uploaded increases.

Growth of distinct tags

Vocabulary FormationFlickr allows social networks and

interest groups.There is a huge potential for social

influence in the development of tag vocabularies.

People can follow updates from their contacts and this promotes constant tagging.

Randomly chosen 2500 people (frequent taggers) are paired with a random contact and a random user.

Vocabulary Formation

Vocabulary overlap distribution for random users and contacts

Tag Categories

Tag Categories

Tag Categories

Tag frequency distribution in Flickr

Number of tags per photo in Flickr

ConclusionSocial tagging systems have the potential to

improve many information systems problems.In order to study these system, the systems

place in the taxonomy of architectures should be observed.◦ Different applications have different tagging

systems and user motivations.Tagging systems could be improved

◦ Preventing problems of meaning◦ Finding relations between the tags (synonyms,

abstractions)◦ Gathering information from the images

QUESTIONS?