There are 4 main types of note, each of which represent a different length of sound (measured in beats):

Crotchet	Minim	Quaver	Semibreve
1 beat	2 beats	½ beat	4 beats

Notes can be laid out on a stave in any order to make interesting rhythms, but can never add up to more of less than the exact number of beats needed in a bar (as suggested by the time signature at the beginning of a piece of music). 

There are 4 main types of rest, each of which represent a different length of silence (measured in beats):

Crotchet rest	Minim rest	Quaver rest	Semibreve rest
1 beat	2 beats	½ beat	4 beats

Rests are combined with notes and can be laid out on a stave in any order to make interesting rhythms, but can never add up to more of less than the exact number of beats needed in a bar (as suggested by the time signature at the beginning of a piece of music). 

Bars are how we divide music into managable, digestable bits. Bar lines divide music into seperate bars, each one resetting the count of a number of beats. The number of beats we cound is always exactly what the time signature explains. 

Staves are 5 lines on which we put notes. These lines tell us a pitch of a sound while the note tells us how long that pitch is played for. The 5 lines on ther own don't mean anything until there is a clef at the beginning.

A Clef is a symbol which defines a range of pitches on a stave. These basically tell us where middle C is and the notes avobe or below it. 

Time signatures tell us how many beats to count in each bar, and what type of note that beat is. They are one number on top of another.

The top number of a time signature can be anything but is usally a small, easily counted number.

The bottom number of a time signature is a 2, 4, 8 or 16. These reflect a specific type of note so a 2 is a minim, a 4 is a crotchet, an 8 is a quaver and a 16 is a semiquaver. 

Key signatures tell us which key a piece of music is written in. They give us a scale of the key, the sharps and flats there might be and the overall harmonic structure we can expect from a piece of music. Keys are a 'best fit' for music and moving away from the key is usual and expected to make music sound interesting to listen to. 

Sharps (♯), flats (♭) and naturals (♮) are symbols places to the left of a note which infer a change in the pitch of that note. A sharp moves a pitch a semitone UP from the note that's written, a sharp moves a pitch a semitone DOWN from a note that's written and a natural will wipe out any sharps or flats from that note if it's already sharpened or flattened.

Musical pitches are divided up into discrete units. The gaps between these are called intervals which we define in terms of tones and semitones.

A semitone is the smallest interval in western music and is from one pitch to another where there's nothing inbetween. For example a B to a C with nothing in between.

A tone is an interval which has 1 note in between, for example going from C to D with the C♯ inbetween.

Dynamics are how music is played.

These are usually terms and symbols which indicate changes in volume or speed.