The GeoJSON-LD project

JSON-LD is JSON for linking data and it's a web standard: http://json-ld.org/. It offers a smooth, even zero-edit in some cases, path for upgrading existing GeoJSON data and makes web-friendly extension of GeoJSON possible.

Previously, if you added a "timestamp": "2014-03-27" to a GeoJSON feature object's "properties", a user has to guess what you mean. Playing guessing games with my kids is fun. Playing pointless guessing games with data sucks. One of the most important things JSON-LD offers is a framework in which you can unambiguously identify "timestamp" as "http://purl.org/dc/terms/created". Now users of your data have a solid start toward understanding what you mean by "timestamp".

There's more to JSON-LD than defining your feature properties. You can also bring in terms from other vocabularies to express that your features are, say, schema.org AdministrativeAreas or Landforms.

If you'd like to help shape the way we use GeoJSON in the future, please follow https://github.com/geojson/geojson-ld and jump into discussion on the open vocabulary and context issues.