A GTFS feed is composed of a series of text files collected in a ZIP file. Each file models a particular aspect of transit information: stops, routes, trips, and other schedule data. The details of each file are defined in the GTFS reference.
See GTFS Examples for model feeds that illustrate GTFS usage. A transit agency can produce a GTFS feed to share their public transit information with developers, who write tools that consume GTFS feeds to incorporate public transit information into their applications. GTFS can be used in a variety of applications & processes (see GTFS Applications, below).
Many applications are compatible with data in the GTFS format. The simplest way to make a feed public is to host it on a web server. Developers and consuming applications can download GTFS data from the specified URL.
The best method to quickly share a GTFS dataset with a large number of developers is to register the zip file URL via websites that serve as the primary global directories of publicly accessible GTFS data:
A partial directory of the many applications that consume and utilize GTFS data is maintained at TransitWiki.
Many types of applications consume GTFS data, including:
There are a number of mailing lists that can be good resources when you have questions about public transit data, software, formats like GTFS and GTFS-realtime, and other issues:
Transit Developers: general transit developer discussions. Many transit agencies also have their own developer mailing lists specific to the agency. For example: