Ardour offers three track types depending on the type of data they contain, and differentiates between three track modes, depending on their recording behaviour.
An Ardour track can be of type audio or MIDI, depending on the data that the track will primarily record and play back. However, either type of track can pass either type of data. Hence, for example, one might have a MIDI track that contains an instrument plugin; such a track would record and play back MIDI data from disk but would produce audio, since the instrument plugin would turn MIDI data into audio data.
Nevertheless, when adding tracks to a session, you typically have an idea of what you need to use the new tracks for, and Ardour offers you three choices:
If you add an instrument plugin, the MIDI track outputs audio instead of MIDI data.
Audio tracks in Ardour have a mode which affects how they behave when recording:
The screenshot on the right shows the subtle difference between an overdub
in normal mode (upper track) and one in non-layered mode
(lower track). Both tracks were created using identical audio data.
The upper track shows a new region which has been layered on
top of the the existing (longer) region. You can see this if you look
carefully at the region name strips.
The lower track has split the existing region in two, trimmed each new
region to create space for the new overdub, and inserted the overdub region
in between.
Ardour tracks can have any number of inputs and any number of outputs, and the
number of either can be changed at any time (subject to restrictions caused by
any plugins in a track). However it is useful to not have to configure this sort
of thing for the most common cases, and so the
Add Tracks dialog allows you to
select "Mono", "Stereo" and few other typical multichannel presets
The name of the preset describes the number of input channels
of the track or bus.
If you have configured Ardour to automatically connect new tracks and
busses for you, the number of outputs will be determined by the number of
inputs of the master bus,
to which the track outputs will be connected.
For example, if you have a two-channel master bus, then a Mono track has one
input and two outputs; a Stereo track has two inputs and two outputs.
If you you set Edit > Preferences > Audio > Connection of Tracks and Busses to manual, then tracks will be left disconnected by default and there will be as many outputs as there are inputs. It is up to you to connect them as you wish. This is not a particularly useful way to work unless you are doing something fairly unusual with signal routing and processing. It is almost always preferable to leave Ardour to make connections automatically, even if you later change some of them manually.