REAPER <https://www.reaper.fm> is a Digital Audio Workstation (DAW) made by Cockos. It is a feature-rich DAW offering many tools and a high flexibility in use and configuration. Besides it is also highly extendable through an extensive API <https://www.extremraym.com/cloud/reascript-doc/#CSurf_OnRecvPanChange> which can be used to write custom extensions and scripts written in LUA, EEL or Python.
Tracks in REAPER
In most DAWs you differentiate between Audio-tracks, MIDI-tracks, Mixbus-tracks, ... In contrast Tracks in Reaper can be used for everything and just the routing defines which role a track might have in project.
Per default a track is a stereo track (there are no mono tracks) and all tracks are route to the Master- or Parenttrack. (keep that in mind!)
Every track can be configured to have two or up to 64 channels. to configure channel number press the Route button
Every track can send its audiochannels to * Master-/Parenttrack * Hardwareoutput * Any other track
Any channel and any number of it can be send. in the route window choose new send to track or new hardware output the number of channel is set after the creation of the send