Extra Lights - Most likely a little thinner than what your guitar came with new. A bit easier to play/bend, but will also have a little lighter tone. Lights - MOST NEW GUITARS COME WITH LIGHTS. By far the most popular gauge of string. Light enough for easy playing, but thick enough for a good full tone. Our recommendation if you're unsure. Mediums - In the acoustic world, this is the heaviest standard gauge of string. Firmer to play, but will also give you a nice full tone. Many heavy strummers prefer mediums. Want extra lights or mediums? Check out our other listings, we have it all!