The VS1053 can decode a wide variety of audio formats such as MP3, AAC, Ogg Vorbis, WMA, MIDI, FLAC, WAV (PCM and ADPCM). It can also be used to record audio in both PCM (WAV) and compressed Ogg Vorbis. You can do all sorts of stuff with the audio as well such as adjusting bass, treble, and volume digitally. There is also 8 GPIO pins that can be used for stuff like lighting up small LEDs or reading buttons.
The breakout is slim enough to fit on a breadboard with 1 row of holes left over for wiring. There's 3.3v and 1.8v regulators onboard with ferrite beads and analog filtering for quality analog output. There's a microphone input port that you can wire up a line-in or mic to and record compressed audio. All 8 GPIO are broken out and they all have built in 100K pulldowns, simply connect your button from the GPIO pin to 3.3V for an active-high connection. You'll likely want to play music from a microSD card so we added a holder on-board. And since we know so many of our customers use 5V microcontrollers like the Arduino, we made the interface pins all 5V compliant with level shifters so you can use the chip at 3V or 5V power/logic!