Prelude (noun)

1. A piece of music, typically one that is short and at the beginning of a longer work, that serves as an introduction.
2. An action or event that precedes and is seen as an introduction to another.

Origin:

Late 16th century: from french prélude, or from latin praeludium, from prae "before" + ludium "a game", "a song".

Examples:

1. A prelude to a concerto.
2. A prelude to a storm.
3. Prelude to a major work.
4. Prelude to a negotiation.
5. A prelude to a speech.