Tempo, Time Signature and Note Values
“Duration” – the “length” of each note – is the second basic property of all notes. (The first was “pitch”.)
If you tap your foot at a consistent rate of, say, 60 taps per minute (once every second), that would be called a tempo of 60 bpm (beats per minute). Each of these beats is represented in written notation as a quarter note.
Traditional written music is divided into what are called “measures” (or “bars”). Each measure is a short chunk of the composition containing a set number of beats. The simplest and most common measure contains 4 beats.
When a note is held for the entire measure is called a whole note. When it is held for half a measure is called a half note. And when it is held for a quarter of a measure – one standard “beat” – is called a quarter note*.
This graphic shows how each of these notes is indicated on the staff:
The quarter note is one beat* long, is usually the most common note in a composition, and is the basis for other note durations. A quarter note can be divided into two eighth notes or four sixteenth notes.
These can be further divided into even shorter note durations: 32nds and 64ths. But for beginning guitar players the 16th is usually the shortest note encountered in simple songs.
Many musical compositions are written in what is called 4/4 time – where each measure contains 4 quarter notes. The 4/4 you see at the beginning of each staff is called a “time signature”.
While 4/4 time this is the most common (and, in fact, is called “common time”), it is not the only one found in music. For instance, a “waltz” is written is 3/4 time (3 quarter notes per measure).
Rests – where you don’t play anything
The other important element of written music is the rest. A rest indicates when you don’t play a note. It is “dead air space”.
Each note value (whole, half, quarter, eighth, sixteenth) has a comparable rest. They are signified on the staff as in the following graphic:
Here is a graphic showing most of the elements you are likely to encounter as you learn to read traditional music notation:
*It is technically not correct to say a quarter note is always one beat in duration. As Widipedia says, “Often, musicians will say that a crotchet [quarter note] is one beat, but this is not always correct, as the beat is indicated by the time signature of the music; a quarter note may or may not be the beat.” For practical purposes the beginner can ignore this technicality.