  Context. This paper presents an overview of the photometric data that are
part of the first Gaia data release. Aims. The principles of the processing and
the main characteristics of the Gaia photometric data are presented. Methods.
The calibration strategy is outlined briefly and the main properties of the
resulting photometry are presented. Results. Relations with other broadband
photometric systems are provided. The overall precision for the Gaia photometry
is shown to be at the milli-magnitude level and has a clear potential to
improve further in future releases.
