Semibreve (1 Note)
A whole note or semibreve is represented by a hollow oval note head, like a half note (or minim), but with no note stem.
Its length is equal to four beats in 4/4 time.
Most other notes are fractions of the whole note; half notes (or minims) are played for one half the duration of the whole note, quarter notes (or crotchets) are each played for one quarter the duration, etc.
Minim (1/2 Note)
A half note or minim is played for half the duration of a whole note (or semibreve) and twice the duration of a quarter note (or crotchet).
Half notes are notated with a hollow oval note head (like a whole note) and a straight note stem with no flags.
All notes with stems are drawn with the stems to the right of the note head when facing up, when they are below the middle line of the staff. When they are on or above the middle line, they are drawn with stems on the left of the note head, facing down.
Crotchet (1/4 Note)
A quarter note or crotchet played for one quarter of the duration of a whole note (or semibreve).
Quarter notes are notated with a filled-in oval note head and a straight, flagless stem.
Quaver (1/8 Note)
An eighth note or a quaver is played for one eighth of the duration of a whole note (or semibreve).
Eighth notes are notated with an oval, filled-in note head and a straight note stem with one flag note.
On stems facing up, the flag starts at the top and curves down to the right. On downward facing stems, the flags start at the bottom of the stem but still curves to the right. When multiple eighth notes are next to each other the stems may be connected with a beam rather than a flag.
Semiquaver (1/16 Note)
A sixteenth note or semiquaver is a note played for one sixteenth the duration of a whole note (or semibreve). The semiquaver is half of a quaver which is an eighth note.
Sixteenth notes are notated with an oval, filled-in note head and a straight note stem with two flags. The same rules apply to smaller divisions such as thirty-second notes or demisemiquavers and sixty-fourth notes or hemidemisemiquavers. Each time the note is halved an extra flag is added.