REAPER is a digital audio workstation: a complete multitrack audio and MIDI recording, editing, processing, mixing, and mastering environment. Using your current computer and no other software, you can import any audio and MIDI, synthesize, sample, compose, arrange, edit, mix, and master songs or any other audio projects. If you add a hardware audio interface of your choice (AD/DA: analog-to-digital/digital-to-analog) and a microphone, you have a complete recording studio, suitable for recording anything from a soloist to a band to an orchestra (even if the orchestra is just you).

REAPER converts your computer into the full power of any top-of-the-line recording studio. Minus, of course, a room full of shockingly expensive converters, microphones, amplifiers, and, well, talent. If you are a top-of-the-line recording studio interested in REAPER, this part of the discussion has probably insulted your intelligence.
So we'll just say that unlike some other DAWs, REAPER will support almost any existing audio interface, even interfaces manufactured by companies whose software does not allow you to use any other hardware interface.

Nondestructive multi-track recording means that you can record and layer take after take, correcting, editing, revisiting, and tweaking to your heart's content. There are inexpensive audio interfaces designed just to plug guitars in to, and there are very fancy audio interfaces designed to convert many simultaneous line and microphone inputs.

REAPER is designed to let you work quickly and creatively, without imposing any artificial limits on what you can do. REAPER doesn't have track types, busses, tools, or offline processing. If you want to create a drum bus, simply add a track above the drum tracks and press the folder button - the drums will automatically send to the folder, Once you get the drum levels and FX tweaked right where you want them, you can record the folder's output to non-destructively freeze the drums and move on.

Fast, Powerful Editing:
• Drag and drop to import, arrange, and render
• Freely mix audio, MIDI, video, still image media on any track
• Easily move, split, glue, resize, trim, loop, time stretch, pitch shift, fade, crossfade, slip, snap to grid, without switching tools
• Intuitive zoom, scroll, scrub, jog, tab to audio transient, MIDI navigation
• Simple and powerful nested folder system allows group editing, routing, bussing, all in one step
• Full automation recording, playback, and editing support for track controls and plug-ins
• Easily manage tempo, time signature, and varispeed changes
• Separate audio or MIDI into freely arrangeable takes and lanes for easy comping
• Easily copy or move regions, to quickly try out alternate arrangements

Plug-in Support:
• Insert almost any third-party audio or MIDI plug-in: VST, VSTi, DX, DXi, AU (OSX only), JS
• ReWire (audio and MIDI) any capable application for even more flexibility
• Fully automatic plug-in delay compensation (PDC)
• Sidechain any plug-in, even if the plug-in does not natively support sidechaining
• Apply FX in real time, or non-destructively render FX output
• Real-time network FX processing: use other local machines as an FX farm

64-bit ReaPlugs Suite:
• Unlimited multiband EQ with draggable nodes
• Graphical FFT EQ/dynamics processing
• Technical and multiband compression
• Flexible, open-format convolution reverb
• Real-time pitch correction, with Elastique 2 Pro built in
• Multitap delay, basic synthesizer, sample player, vocoder, algorithmic reverb, and more
• Special-use plug-ins to virtualize outboard hardware, stream audio, connect to NINJAM servers, and more
• Includes the JS audio and midi plug-in scripting engine, and hundreds of user-programmable effects

Intangibles:
• REAPER starts and loads fast - be ready to record in just a few seconds
• Portable - put REAPER in your pocket and run it from a USB key or other removable media
• Tightly coded - installer is only a few MB, updates can be installed in less than a minute
• Rapid, efficient development - new features and optimizations are added quickly and often
• Very active, enthusiastic, and helpful user forum, get help quickly
• Fantastic and readable user-created manual
• An honest business model that aims to provide the best possible user experience