Audacity

I love the name but I also love the software.  It’s easy to record separate tracks and to listen to tracks and add new ones.  It’s easy to shift tracks in time.  All the effects are there from reverberate to pitch-shift to fade out to a whole bunch that I don’t understand yet.  You can generate and read pretty much all the open formats.  All in all it’s a lot of fun.  And hey!  It’s free.