Intonation

Getting a clean reading: play one string at a time and let it ring — the tuner needs a steady tone, and it will jump around if two notes overlap or the room is noisy. Pluck at moderate strength rather than hard; a hard attack starts sharp and settles flat, so the reading drifts for the first second. Cents are hundredths of a semitone, and anything within about five either way is close enough that an audience won't hear it. For guitar and bass, tune up to the note rather than down — coming up from below takes the slack out of the tuning peg and the string holds better. The reference field matters if you're playing with a piano tuned to something other than 440, or in an ensemble that tunes to 442.