Before you begin each lesson or a practice session you must tune your guitar. If your guitar is out of tune everything you play will sound incorrect even though you are holding the correct notes.
If you want to play along with a teacher or other musicians, your guitar must be tuned to "concert pitch." This is a standard tuning that all musicians tune to so that they can play "in concert" with each other. It is possible for a guitar to be in tune with itself (e.g., you strum a chord and it sounds in tune) but out of tune with a piano which would be tuned to concert pitch. the following examples are methods you can use to tune to concert pitch i.e., electronic tuner, tuning to another instrument, tuning fork and pitch pipes. Also discussed is a method of tuning all guitarists must know, i.e., tuning the guitar to itself. This tuning method is essential to know because when tuning to concert pitch you may only be given one note (usually the open 5th string A) so you have to know how to tune the other strings to this note.
If you are playing along with another instrument, it is essential that your guitar be in tune with that instrument. Tune the open strings of your guitar to the corresponding notes of the accompanying instrument. E.g., to tune to a piano, tune the open 6th string to the E note on the piano, as shown on the keyboard diagram. Then tune your guitar to itself from this note using the method outlined on the following page, or tune each string of your guitar to those notes of the piano shown on the keyboard diagram.
A tuning fork produces a note usually the 5th string A Note) which you tune one string to. Then you tune the other strings to that string.
Pitch pipes produce notes that correspond to each of the six open strings.
Unless you are using an electronic tuner, to be able to tune the guitar accurately usually requires many months of practice. You will probably need your music teacher or musician friend to help you tune when you are learning.
If you do not have another instrument to tune to, you can tune the guitar to itself by using the following method.