Deprecated features

OpenStreetMap does not have "banned features", as anybody is allowed and encouraged to use any tag they think is useful.

However, from time to time the community of mappers suggests a new feature instead of an older one, to improve tagging clarity or structure. If there is no strong reason to stick to the old tags in these cases, you might want to go along with the recommendation and use the new tags suggested here.

Tags are typically discussed within wider community, for example at tagging mailing list in way that allows everybody to contribute. In cases of consensus that tagging in a different way is preferable tag can be considered as deprecated. There are various ways that together result in reduced tag usage and each requires consensus or agreement from relevant people

Tag can be described as unwanted together with reasons for that on OSM Wiki
Validator complaints may be added to JOSM, iD, Osmose and other validators or other Quality assurance tools
- Typically it requires opening issue on bug tracker of a given project
Support may be dropped from presets and rendering of editors
- Typically it requires opening issue on bug tracker of a given project
People may check tag usage in their area and edit objects to improve tagging
In rare cases automatic edits can be done to improve tagging. Such edits must follow Automated Edits code of conduct

Examples

There are some clear cases like highway=unsurfaced that has

no support among mappers
usage minimal compared to alternatives
conflicts with widely used tagging schemes for describing roads
no support by editors
no support by data consumers
validators complain about it when this tag is used

All this is a clear evidence that this tag is deprecated. As result it is described as a deprecated on this wiki.

On the other hand highway=motorway is clearly not deprecated

Massive and ongoing use by mappers
No viable alternatives
No conflict with other serious tagging schemes
Supported by editors
Supported by data consumers
No validator complains about its use

As result it is not described as a deprecated on this wiki.

Wiki guidelines

Please also keep the description box in sync:

You may also use Template:Deprecated on the feature page.

In general, tags should be described as deprecated because there is no serious support for them among mapppers. Opposite - documenting tags as deprecated on OSM Wiki and demanding mappers to change opinion is unwanted.

Everything is more complicated than expected

Opinion among mappers may differ by region - there is a clear consensus that associatedStreet relations are unwanted in Germany but at the same time mappers in France like it and continue to use this tagging scheme.
In some cases opinions of mappers are not nicely segregated in regions and mappers in the same area has different preferences. This is case most likely to result in conflicts.
Some tags may be supported or preferred in one editor, while other software may encourage to use a competing tagging schemes
In some cases validator complaints are unwanted and should be changed See for example this case where describing some tag combinations as deprecated was reverted. In general for any validator it is sometimes necessary to improve validator, not map data
Some tags with very high usage count are considered as deprecated - for example is_in=* tag family is considered as deprecated by JOSM.
Sometimes opinion among mappers or group of mappers conflicts with opinion among developers of validator or QA tool. Sometimes different group of mappers request opposing changes to what kind of mapping should be considered as undesirable.
Just describing something as deprecated on Wiki does not make tag deprecated
Data consumers may lag behind what is preferred among mappers or present in database, sometimes very significantly. Note also that some projects consider providing useful feedback to mappers as important goal (for example OSM Carto) while other map projects may have different priorities.