Notes are played from left to right across
the stave. As we have seen the vertical position of the note tells
us which note to play, the 'shape' of the note (its stem and number
of tails) shows us how long to play it for.
The longest note is the semibreve all the other
notes are smaller divisions of time of this note (a semibreve
is twice as long as a minim, a minim is twice as long as a crotchet
and so on).
For example four crotchets are equal in time to
one semibreve, that means a crotchet note is played for only one
quarter the time a semibreve note is played. So four crotchets
are played in the same time it takes to play one semibreve.
A note with a dot placed after it, is played for
one and a half times its normal length, in other words the dot
adds half of it's original 'time value' to the note.
Each note has its own 'rest' shape that has the
same 'time value' but indicates no note (or a rest) is played
at that point in the music.