Why are medicines used ?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Purpose of Medicines:**
Medicines are substances used to diagnose, treat, or prevent diseases. They play a crucial role in maintaining health and managing illnesses.

2. **Three Main Functions of Medicines:**
Medicines can be categorized based on their primary functions:
- **Prevention:** Medicines can prevent diseases. Vaccines are a prime example of preventive medicine. They help the body develop immunity against specific diseases. For instance, vaccines for polio and COVID-19 are designed to prevent these illnesses.
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