Music is like a language:
 people compose music to say something to other people or make them feel a certain way.
In the language of music, notes are like the letters of an alphabet, and they are grouped together into musical ideas that make sense to our ears,
 just like letters are grouped together into words, phrases, and sentences.

MELODIC PHRASES

Groups of words that form a whole idea that makes sense may be a simple, complete sentence, or may be a major phrase in a more complex sentence;
 groups of notes that make a whole musical idea that makes sense are called phrases.
Just as you pause at the period at the end of the sentence (or at the comma at the end of a long phrase when you are reading),
a melody also often pauses slightly when it comes to the end of a phrase, called cadences.

Two melodic phrases are called PERIOD.
The phrases of the music are also grouped together into more complete ideas (like a question and answer).