Tracks are selected by clicking on the Track header at the left of the Editor window. Multiple tracks can be selected with Left clicks, or a range of consecutive tracks with Left.
By default, selecting regions has no impact on track selection. A track can be selected, then a region in another track (or vice versa) and both selections will co-exist happily. Operations that are applied to tracks will use the track selection, and those that apply to regions will use the region selection. Similarly, deselecting a region will not deselect the track it is in (if that track was selected).
Is it still true ?
In some workflows, and particularly in comparison with other DAWs, this is not the most comfortable way to work. You may prefer to work in a style where selecting a region will also select the track that the region is in. Similarly, when the last selected region in a track is deselected, the track will also become unselected.
To control this behaviour, set Edit > Preferences > Editor > Link selection of regions and tracks.
This menu doesn't exist anymore