Headphones, once considered simply an accessory, have become a necessary part of virtually every musician's toolbox. From tracking to practice sessions to live monitoring to mixing—you need at least one great-sounding pair of “cans” to offer a new perspective on the music you make. But choosing a pair can be tricky, depending on the intended application and what your level of physical comfort with different styles is.
In-ear phones, sometimes called "earbuds" or "earphones," are the smallest, lightest and least conspicuous choice. They're definitely the best choice for onstage wireless monitoring or for personal listening while on the go. Advances in technology for fit options make for superb isolation. The seal with your ear can make for exaggerated frequency response, so in-ears haven't historically been the first choice for mixing or reference-quality listening, but new technology and the reduced size of transducers, making for up to 5 individual drivers per ear, have made critical listening on in-ears a possibility.
Fit is critical for any set of earphones, as better fit means longer comfort. There are several fit strategies, from interchangeable foam and silicon rubber inserts for different-sized ear canals and different degrees of softness to over-ear loops that provide a secure fit without the phones having to be quite so close a fit to the ear canal.
When considering earphones with an ear towards accuracy and even frequency response, consider pairs with multiple drivers. Like 2- and 3-way monitors, each driver handles a different section of the frequency spectrum, making for better and clearer overall sound.