Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Describe the Aztec calendar

### Response:
The Aztec calendar was an adaptation of the Mayan calendar, used by the Aztecs and other Pre-Columbian people in Central Mexico. It was a 365-day calendar that was divided into 18 months, each with 20 days. The remaining 5 days were considered unlucky and were not part of the regular year. The calendar was used to note important religious and social events, as well as keep track of time.