Good information on tuning a guitar or bass to standard of drop D.
Tuning a guitar to the perfect pitch can be difficult, especially if you have never done it before and do not know how. To start out in standard tuning, you need to tune the top string to E using whatever you have. If you do not have a tuner, find an E on a piano or an E in a song. Adjust the tuning peg until the string sounds the same as the note your using.
Once the top string is tuned to an E (6th string), you can start tuning the other strings using the E string. The next string down, which is A (5th string), is the same note as the fifth fret on the E (6th) string. So if the E (6th) string is tuned correctly, you can tune all the other strings easily. Play the fifth fret on the E (6th) string then play the open A (5th) string, now tune the A until it sounds just like the fifth fret on the E string. Most of the strings can be tuned like this, all except for the B (2nd) string. Repeat that Pattern on the next two strings. Use the fifth fret on the A string to tune D (3rd string), and the fifth fret on the D string to tune G (4th string). When you get to the B (2nd) string, do the same thing only using the fourth fret on the G (4th) string instead of the fifth fret. This is because the note E has no Sharp, and the second fret on the G (4th) string is an E. Therefor, the fourth fret is B instead of the fifth. After tuning the B (2nd) string, tune the high E string the same as all the others using the fifth fret on the B (2nd) string.
Another way to tune your guitar or make sure it is still in tune is by using the harmonics. Harmonic pitches happen when you place your finger gently on top or the string without pushing down and pluck a string. Then quickly take your finger off of the string and you will hear the harmonic. The reason you can tune your guitar with this is because the harmonic of the fifth fret on the E ( 6th) string is the same as the harmonic of the seventh fret on the A (5th) string. All the strings can be tuned in this way once again except for the B (2nd) string. Tune the B (2nd) string using the first method.
Drop D tuning is a simple alternative tuning that normally gives a heavier sound to the playing. Without using a tuner there are two ways to tune to Drop D. When tuning to drop D, all you are doing is dropping the low E (6th) string one whole step (note) down. This makes the seventh fret on the E (6th) string the same note as the open A (5th) string. Tune the E (6th) string down a little and see if they match, if they do not, just keep adjusting the string until the seventh fret on the E (6th) string matches the open A (5th) string.