OpenStreetMap is a community-driven alternative to GoogleMaps. It is essentially Wikipedia for spatial data. Like Wikipedia, anybody can contribute new geographic data or refine the existing data. All of OpenStreetMap's data is open data, licensed under their "Open Data Commons Open Database License," which is broadly similar to a Creative Commons Attribution-ShareAlike license. Users may copy, distribute, transmit, and modify the data provided that they credit OpenStreetMap. Modified versions of the data must be distributed under the same license. Users that don't want to download the full 64 GB data file can select from a number of smaller "extracts" or use the OpenStreetMap APIs to access the data online. Numerous desktop and mobile applications understand this API and a full list is available on the OpenStreetMap wiki. Users interested in contributing to OpenStreetMap may be interested in the projects category on the wiki for a list of ongoing projects (for example, wheelchair-friendly walking routes, US railways, historic battlefields, and dozens more).