This is the software publisher's description.

REAPER is a powerful but sensible Windows application designed for the recording, arranging, editing, mixing and rendering of audio.

REAPER provides a flexible but easy to use interface that is equally suited to amateurs and professionals alike.

Some key benefits of REAPER are:

• Easy to use: simply drag and drop one of many kinds of files to edit existing material, or insert a track and arm it for recording. No complex project or definitions to set up.
• Fast and powerful editing facilities: split, resize, fade/crossfade, pitch shift, timestretch, copy/paste and loop media items with ease. Ripple editing is available, too.
• Unrivaled routing capabilities: send tracks to any number of other tracks or hardware outputs, with lots of options (pre-fx, post-fx, independent faders, mono or stereo). Not interested in advanced routing? You don't have to use it (and it certainly won't get in the way.)
• Powerful recording options (supports pre-fx, post-fx recording, can record mixed output of multiple tracks, etc), supports switching record inputs/modes on the fly, input monitoring options (including tape-style auto input monitoring mode), supports auto-punch-in/punch-out, and more. If you want. Otherwise, it just behaves as you would expect.
• Support for MIDI files, recording MIDI, and VSTi/DXi softsynths. MIDI can be integrated and mixed with audio.
• Support for consolidating track edits and rendering track stems, to enable easy export for other applications.