GeoNames is an online, free, and collaborative gazetteer (i.e. a geographic database). For each place/entry, GeoNames provides information about geo-coordinates, variant names in several languages, administrative relationships, and geo-physical features. Unlike other gazetteers that have a specific spatial scope, GeoNames aims to cover the whole globe, sometimes achieving an impressive level of granularity. In GeoNames, each entry is also represented as a single web resource, and receives an individual and stable URI (Unique Resource Identifier). This has made GeoNames a very important component of the semantic web, and a widely used resource in different kind of applications. In the development of historical gazetteers, for example, GeoNames plays a crucial role as backbone, to facilitate alignment and comparison. It is very common to use GeoNames identifiers as references for academic endeavors like the Pleiades Gazetteer of the Ancient World, as well as larger scale project like Wikidata itself.
Although GeoNames focuses explicitly on contemporary data, and doesn't have interest in former locations or ancient names, it also features some major monuments and a number of (still extant) archaeological sites.
Data in GeoNames are entered and curated by the community through a wiki interface, and they can be downloaded and reused, under CC licence. Among various applications of this rich dataset, GeoNames is one of the gazetteers exploited by Pelagios in both its visualisation API, Peripleo, and its annotation platform, Recogito. The latter, however, only features subsets of the GeoNames data.