What is heat period?

Explanation

### Step-by-Step Solution:

1. **Definition of Heat Period**: The heat period, also known as the estrous cycle, refers to the specific time in the sexual cycle of female mammals (excluding higher primates) when they are receptive to mating.

2. **Characteristics of the Heat Period**: During this period, females are in a state known as "in heat," which means they are ready to accept a male for mating.

3. **Occurrence**: The heat period can occur multiple times during the breeding season of certain species.

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