A symphony is an extended work for an orchestra consisting of string instruments, woodwinds, brass and percussion. It typically has four segments, based on four different tempos: 1) fast; 2) slow; 3) moderate to lively; and 4) fast to very fast. These four segments, or ‘movements’, are associated, respectively, with drama; expressivity and sensibility; physicality; and conviviality.
A string quartet is an extended work for two violins, a viola and a cello. It is commonly organised into the same sequence of four movements found in symphonies.
A concerto is a multi-movement work for a soloist and an orchestra. Usually, the number of movements is three rather than four.
A sonata is a multi-movement work for a piano soloist, or for a soloist playing a different instrument and accompanied by piano.
An overture is a symphonic introduction to an opera, ballet or play. A tone poem is a shorter, free-standing work for orchestra. These tend to follow the dramatic pattern typical of symphonic first movements.
Preludes, études (studies) and character pieces are short compositions, typically for piano.