Tag an Object

Best Practice · Last modified February 25, 2010

Allow users to add their own tags (keywords) to an object. Be clear about how to separate (delimit) distinct tags. Consider allowing people to tag objects they did not create or don't own, with the permission of the creator or owner. Don't be afraid to mix a controlled vocabulary with user-generated tags.

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What Problem Does This Solve?

A user wants to attach their own keyword or set of keywords to an object for organization and later retrieval.

When to Use This Pattern

  • Use this pattern when a user is collecting a large amount of unstructured data, such as photos.
  • Use this pattern when a user wants to manage a large collection of items, like books
  • Use this pattern to blend user generated labels and keywords with structured metadata.

What's the Solution?

  • Allow users to add their own tags to an object.
  • Allow users to delete tags they have associated with an object. This allows for deletion of duplicates or misspellings.
  • Provide very clear instructions for how to separate distinct tags. There are two methods currently popular across the web right now - comma delimited and space delimited. Either of these can be used, but be consistent and very clear in labels as to which is being used. There is nothing more frustrating than thinking the delimiter is a comma and entering a multiword tag only to have it separated out into multiple tags thereby changing the meaning or intent of the tag.
  • For more robust social engagement, allow connections and/or friends to tag objects in a collection.
  • Don't be afraid to mix a controlled vocabulary - defined by the site architects - with user-generated tags.


  • Adding tagging to objects as a product feature should offer a benefit to the user. Do the tags help her find and manage her collection? Do the tags tighten the circle of community? Tagging as a user activity is more successful when there is a payoff to the user and their friends.
  • Provide tag hints if the item being tagged is a public item (a news article, a bookmark). Delicious shares recommended tags or previous tags associated with the object so that the user can select from these or simply add to the collective tag set for the object.
  • Tags and the ability to add a tag mechanism should be in close proximity to the object being tagged.

Open Questions

Use of a comma versus a space as an item delimeter is still an outstanding question across the web and one standard solution has not emerged. It is unlikely that one will prevail over the other as both are pervasive and have roots to traditional database delimiters which allow several options.

Why Use This Pattern?

Enabling people to freely invent their own keyword tags can lead to a collaboratively curated folksonomy that may help others find what they're looking for.