The most common notes are whole notes, half notes, quarter notes, eighth notes and thirty-second notes. In some countries, these are known as the semibreve, minim, crotchet, quaver, semiquaver and demisemiquaver, respectively.
A whole note is held longest in terms of the time a tone should be played or sung. A half note is played for half the time of a whole note, a quarter note is held a quarter of a whole note's time, an eighth note is an eighth the duration of a whole note and so on.
Just as there are notes that tell musicians when to create sounds, there are symbols to tell a musician when to be silent. These symbols are called rests and the length of time they denote corresponds to the note system: whole rest, half rest, quarter rest and so on.
The whole note only has an oval-shaped symbol to represent it, but the other notes have additional parts. An eighth note, for instance, has an oval part, called the notehead; a stem, which can point up or down; and a flag, which is positioned to the side of the top of the stem.
The parts of a note help you identify what kind it is. A whole note's notehead is hollow, with no stem or flag. A half note has a hollow notehead and a stem. A quarter note has a solid notehead and a stem. All the notes beyond the quarter note have solid noteheads, a stem and at least one flag. The eighth note has one flag, the sixteenth note has two, the thirty-second has three and so on.
When notes are written on a staff, either in the spaces or on the lines themselves, the staff helps you know which tone you are supposed to play. A note written in the top space on the staff will be an E, for instance. To give a musician a guide for notes written above and below a staff, ledger lines are drawn. It's as if, just for this note, extra staff lines are drawn to help you place the note in relation to the others.