Periods: In music theory, periods are two-part musical structures consisting of an antecedent phrase followed by a consequent phrase. They often exhibit question-and-answer relationships.
Antecedent Phrase: An antecedent phrase is the first half of a period and usually ends with an unresolved cadence. It sets up expectations for what will follow in the consequent phrase.
Consequent Phrase: The consequent phrase is the second half of a period and provides resolution to the melodic and harmonic tension created by the antecedent phrase.