Melody
This, of course, is another name for the ‘tune’, but in some circles can also be called a ‘subject’; hence the first tune in a piece of music may also be referred to as the ‘first subject’ and so on.
Key
This will be mentioned a lot, as most music written between the fifteenth century and the middle of the twentieth century is referred to as being ‘in the key of…’. This really means that the piece is based on the notes of a particular major or minor scale with the first note in such a scale giving its letter-name to the key in question.
Scale
The word scale comes from the Latin word scala and literally means ‘a ladder’. When applied to music it is the stepwise arrangement of ntoes within a particular key. There are many kinds of scale, but the ones that are most commonly referred to include major scales (generally happy-sounding) and minor ones (definitely sadder and more mysterious in character). Take it from this that most pieces in a major key are generally brighter in character than those in minor keys.
Other types of scale that are mentioned are ‘whole-tone’ and ‘pentatonic’ scales. These tend to be used by the modern and Impressionist composers and have also been developed by jazz composers. They have a distinctly ‘different’ sound to them.
Chords
Two or more notes sounding together are known as a chord. Chords can take a number of forms. There are those which sound basically acceptable to all of us (such as those found in the music of Haydn and Mozart) and these are known as diatonic. They take their form in a ragular way from notes in normal scales. However, with the advent of romantic composers and those that followed, more and more use of unusual notes within chords was introduced to produce more emotional effects, some composers even using direct clashes of notes (discords) to create tension in their music.
When chords move from one to another, it is called a progression and again, there are standard progressions to which we can all relate; but many composers were searching for new progressions to make their music sound different and consequently more interesting.
Modulation
This is another expression used commonly in the programme notes of a standard concert, and what it means is moving away from the already established keys of the music. So if a piece is based on the key of A-major and, halfway through, the composer subtly moves the music into F-sharp minor or any other key, one would say that the music had modulated.
Dynamics and Expression Marks
Dynamics within a piece of music are the words or indications given by composers to assist the performs in playing the piece in exactly the right level of sound the composer envisaged. There are all sorts of symbols used within the sheet music to denote these inflections. A dictionary of music would provide a comprehensive guide on these.