OpenStreetMap (OSM) is a collaborative project to create a free editable map of the world. Two major driving forces behind the establishment and growth of OSM have been restrictions on use or availability of map information across much of the world and the advent of inexpensive portable satellite navigation devices. OSM is considered a prominent example of volunteered geographic information - wikipedia

Map of Soho, London This map of London was created from OpenStreetMap project data, collected by the community. This map may be incomplete, and may contain errors. Don't rely solely on it for navigation. - wikimedia

Created by Steve Coast in the UK in 2004, it was inspired by the success of Wikipedia and the preponderance of proprietary map data in the UK and elsewhere. Since then, it has grown to over 2 million registered users, who can collect data using manual survey, GPS devices, aerial photography, and other free sources. This crowdsourced data are then made available under the Open Database Licence. The site is supported by the OpenStreetMap Foundation, a non-profit organisation registered in England and Wales.

Rather than the map itself, the data generated by the OpenStreetMap project are considered its primary output. The data are then available for use in both traditional applications, like its usage by Craigslist, OsmAnd, Geocaching, MapQuest Open, JMP statistical software, and Foursquare to replace Google Maps, and more unusual roles like replacing default data included with GPS receivers. This data have been favourably compared with proprietary datasources, though data quality varies worldwide.

# Map Data

Data provided by the OpenStreetMap project can be viewed in a web browser with JavaScript support via Hypertext Transfer Protocol (HTTP) on its official website - wikipedia

OpenStreetMap maintains lists of online and offline routing engines available, such as the Open Source Routing Machine.Out in the Open: How to Get Google Maps Directions Without Google The OSM data is popular with routing researchers, and is also available to open-source projects and companies to build routing applications (or for any other purpose).

# Licensing Terms

All data added to the project needs to have a licence compatible with the Open Database Licence. This can include out-of-copyright information, public domain or other licences. Contributors agree to a set of terms which require compatibility with the current licence. This may involve examining licences for government data to establish whether it is compatible.

# Software

The web site provides a slippy map (tiled web map) interface based on the Leaflet (Leaflet (software)) javascript library (and formerly built on OpenLayers), displaying map tiles rendered by the Mapnik rendering engine, and tiles from other sources including and MapQuest Open. Maps can also be generated offline by a local installation of Mapnik and downloaded map data.

Software used in the production and presentation of OpenStreetMap data is available from many different projects and each may have its own licensing. The application – what users access to edit maps and view changelogs, is powered by Ruby on Rails. The application also uses PostgreSQL for storage of user data and edit metadata. The default map is rendered by Mapnik, stored in PostGIS, and powered by an Apache (Apache HTTP Server) module called ''mod_tile''. Certain parts of the software, such as the map editor Potlatch2 (Potlatch (software)), have been made available as public domain.