Define the Excretion.

Explanation

**Step-by-Step Text Solution:**

1. **Definition of Excretion**: Excretion is the biological process through which organisms eliminate waste products from their bodies.

2. **Purpose of Excretion**: The primary purpose of excretion is to remove toxic substances and unwanted waste that are not useful for the body. This helps maintain homeostasis and prevents the accumulation of harmful substances.

3. **Excretory System in Humans**: In humans, the excretory system comprises several key organs that facilitate this process. The main organs include:
- **Kidneys**: These are responsible for filtering blood and producing urine.
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