OwnTone is a Linux/FreeBSD DAAP (iTunes), MPD (Music Player Daemon) and RSP (Roku) media server.
It supports AirPlay devices/speakers, Apple Remote (and compatibles), MPD clients, Chromecast, network streaming, internet radio, Spotify and LastFM.
It does not support streaming video by AirPlay nor Chromecast.
DAAP stands for Digital Audio Access Protocol which is the protocol used by iTunes and friends to share/stream media libraries over the network.
OwnTone was previously called forked-daapd, which again was a rewrite of mt-daapd (Firefly Media Server).
Visit the OwnTone documentation for usage and set up instructions, API documentation, etc.
If you are looking for help on building OwnTone (not using it), then please see the Installation instructions.