We have mentioned earlier that different kinds of note last for different lengths of time.
In order to measure the lengths of notes we divide up the music into short sections
called bars or measures. This is done with vertical lines called Bar Lines.
The sign after the clef is called a Time Signature (looks like a "C" doesn't it).
This particular time signature can be written two ways, either as you see it above
or as in the example below. Both means the same thing four counts in every bar.
Let me explain, each bar must last the same length of time, and we measure this
time by counting regular pulses or beats and putting the same number of these
beats in each bar. In this example the crotchet or quarter note is worth one beat.
The four at the bottom of the time signature represent quarter notes (crotchets)
and the four at the top tells us that there must be four counts in each bar.
This means that we can combine different kinds of notes in each bar, provided they add up
to the same value as four crotchets.
Other combinations are possible, here are some examples:-
2/4 two crotchet beats per bar, 3/4 three crotchet beats per bar,
2/2 two minim beats per bar, 3/2 three minim beats per bar and
so the list goes on!