The file formats that define GTA V map data, in one reference. Each has its own page; this is the index.

Map data

YMAP - object placements. The 'what's where' file. Most map editing happens here.

YTYP - object type definitions. References from YMAPs. Defines what the object actually is.

YBN - collision data. Separate from visible geometry.

Drawables and assets

YDR - single drawable model. The actual mesh data.

YDD - drawable dictionary. Multiple drawables packaged together.

YMT - metadata. Properties about objects.

Other formats

YFT - fragment data, used for breakable objects. YPDB - posed data. YCD - clip dictionary, used for animations. Numerous smaller formats for specific subsystems.

Most mappers don't touch the deeper formats. The everyday ones are YMAP, YDR, YMT.