Concertinas and accordions are musical instruments in the free-reed family.
“Free-reed” defined
All free-reed instruments make sound by means of metal reeds that are anchored on one end and free to vibrate on the other. Not to get too technical, when you pull and/or push the bellows of a concertina or accordion, you create air movement. Important: That moving air has to go somewhere, so don’t do this without simultaneously pressing down a key or button. The key or button operates a lever that lifts a pad that allows air to move over the associated reed mounted inside the instrument. The air causes the reed to vibrate, which gives you the sound of the note played by that particular reed.
Free-reed virtues
No strings to tune–just pick up your instrument, breathe normally, and start playing. In that respect, concertinas and accordions are ideal folk instruments. A good teacher can help with your learning curve and keep you from developing bad habits, but many people do fine with a book or a DVD and time to practice. With or without a teacher, lots of practice is crucial, so don’t be discouraged if you have to spend a week on “Hot Cross Buns.” When you’re developing muscle memory and acquiring a new motor skill, perseverance is your friend.
Introduction to Concertinas and Accordions 