When you have finished mixing your session, you probably want to export it to a sound file to burn to a CD, upload to the web, or whatever. Session > Export > Export to Audio file(s)… shows the Export Dialog to do this.
You can also export the outputs of multiple tracks & busses all at once via Session > Export > Stem Export….
This tab contains controls for the format of the exported audio file. You can enable more than one format here, in which case each will be exported in turn. Ardour is supplied with a list of export formats, including:
You can also create a 'Preset' consisting of one or more formats. Ardour provides some ready-made presets, too:
When 'Upload to Soundcloud' is ticked on in any format's tab, a pane containing fields to enter in Soundcloud account details (email and password), and what should happen to the uploaded files will become visible.
This tab allows you to select the range (or ranges) of the timeline to export. By default, "session" is enabled—this will export the whole session from the start marker to the end marker.
Here you can choose which outputs (tracks or busses) should be sent to the exported file.
If you chose 'Stem Export', the 'Channels' tab appears slightly differently: in this case each chosen channel (track or bus) is exported to its own file, instead of all channels being mixed together into a single file. You can choose to export either the region contents or the track output here in this case.