Recent improvements in information technologies such as web mapping and location-aware mobile devices have facilitated non-experts to aggregate, share and edit spatial data in a progressively accessible way. Thus, unlike the traditional spatial data production process, data can be generated by each user. This phenomenon as Volunteered Geographic Information (VGI) was introduced for the first time in 2007, by Goodchild. VGI has significant impacts on geospatial data production and sharing as individuals can act as both data producers and users. Despite the benefits and special characteristics, the richness and complexity of volunteered geographic information makes its usage challenging. This paper addresses the main properties and challenges of the volunteered geographic environment based on the literatures.