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Available languages — Tags
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A tag consists of two items, a key and a value. Tags describe specific features of map elements (nodes, ways, or relations) or changesets. Both items are free format text fields, but often represent numeric or other structured items. Conventions are agreed on the meaning and use of tags, which are captured on this wiki.

Keys and values

Tags are for humans as key=value: key and value separated by an equals sign. Sometimes, the key or value is surrounded by quotes to avoid confusion: key="value" or "key"="value"; the quotes (and, indeed, equals sign) are not part of the tag content.

Tags are applied to elements or changesets (i.e., tagging them) resulting in a collection of tags of any size. However, each collection may only contain a key once. Where a tag is not present, there are often considered to be default values or values inherited from parent elements.

The key, therefore, is used to describe a topic, category, or type of feature (e.g., highway or name). Keys can be qualified with prefixes, infixes, or suffixes (usually, separated with a colon, :), forming super- or sub-categories, or namespace. Common namespaces are language specification and a date namespace specification for name keys.

The value details the specific form of the key-specified feature. Commonly, values are free form text (e.g., name="Jeff Memorial Highway"), one of a set of distinct values (an enumeration; e.g., highway=motorway), multiple values from an enumeration (separated by a semicolon), or a number (integer or decimal), such as a distance.

Here are a few examples used in practice:

  • highway=residential a tag with a key of highway and a value of residential which should be used on a way to indicate a road along which people live.
  • name=Park Avenue a tag for which the value field is used to convey the name of the particular street
  • maxspeed=50 a tag whose value is a numeric speed and speed unit. The unit, km/h, is implied, but can be explicitly specified; miles per hour can be alternatively specified by appending mph. Across OSM, metric units are the default.
  • maxspeed:forward=* a key that includes a namespace for maxspeed to further distinguish its meaning.
  • name:de:1953-1990=Ernst-Thälmann-Straße a tag with the name key suffixed namespaces to specify the German name which was valid in some years.

Finding your tag

The following resources are often used to find an appropriate tag or explore tag usage:

Use in an editor

Some OSM editors (for example iD, Potlatch 2) hide the tags of objects by default, making them not directly editable; instead users fill-in a form. However, likely all tags can be displayed and edited by entering an "advanced" mode of your editor. For the example editors this feature is named “All tags” (bottom left), in iD, respectively “Advanced”, in Potlatch 2.

Node · Way · Area · Relation (members and roles) · Tag (key and value)