WAV is an uncompressed, lossless audio format that preserves the original recording quality. It is widely used in professional audio environments.
Because nothing is compressed at all, the files are large: a normal track runs to somewhere around 30 to 50 MB, roughly ten times a 320 kbps MP3. In a studio that does not matter. In a DJ library of several thousand tracks it adds up quickly, which is why FLAC is usually the better choice for storage, since it is equally lossless in a fraction of the space.
The bigger practical catch is metadata. WAV was never designed to carry tags, and while most software will write artist, title and other fields into it, the handling is inconsistent enough that tags can silently fail to travel between programs. If your library organization depends on tags, comments or key information surviving a move, AIFF is the safer uncompressed format.
Compatibility itself is not a problem. WAV is on every major supported-format list, including rekordbox, Serato and Traktor, and unlike FLAC it exports to USB for club players without restriction. The one thing to watch is sample rate: high-resolution WAV files at 88.2 or 96 kHz only play on newer media players, so a standard 44.1 kHz file is the safer thing to carry.
See Also
AIFF, Lossless Audio, and file format