Melody is a series of pitches organized as a recognizable unit. Each melody has a starting point, stopping point, shape, direction and range. Melodies are not randomly constructed. Instead, they are determined by the parameters of the composition. A musical composition may consist of more than one melody, although multiple melodies are usually linked by other elements of the composition such as the scale and rhythmic pattern. A melody also relies on rhythmic patterns for cohesiveness.
Harmony is how chords are constructed. A chord is a series of at least three notes occurring simultaneously that also supports a melody. Harmony is a key characteristic of Western music. The music of some cultures does not contain harmony at all, just melody and rhythm. The harmonic system of Western music has evolved over a period of several hundred years. Today, harmony is predominately constructed using the interval of a third, which refers to the distance between the notes.
Rhythm is the flow of the sonic action through time. There are several main aspects of rhythm including beat, meter, tempo and accent. The beat is the regular occurring accents of a musical composition. The meter is determined by the strong and weak accents of the pulse. For example, a quadruple meter will have four beats with the strong beats occurring on counts one and three. The tempo is the rate of the pulse. The accents refer to which beats are stressed. Syncopation occurs when the weak beats are stressed.
The sound of a musical composition refers to the timbre or instrumental texture. Each musical instrument or human voice has its own timbre. Even though a clarinet may be playing the same pitch as a trumpet, the timbre is what makes the instrument sound unique. Musical compositions are usually composed with a specific sound in mind, whether it's for a voice, a symphony orchestra or a solo instrument.
Musical texture refers to how many lines of music are occurring in a musical composition. A musical composition may be monophonic, homophonic or polyphonic. A monophonic texture consists of a single melody that isn't supported by any accompaniment. When two or more melodies occur simultaneously the texture is polyphonic. A homophonic texture consists of a single melody with an accompaniment.