What are carcinogens?

Explanation

### Step-by-Step Solution:

1. **Definition of Carcinogens**: Carcinogens are substances that can lead to cancer. The term "carcino" refers to cancer, and "gen" refers to something that produces or causes.

2. **Types of Carcinogens**: Carcinogens can be classified into different categories based on their nature:
- **Physical Carcinogens**: These include agents like UV rays from the sun. Excessive exposure to sunlight can lead to skin cancer.
- **Chemical Carcinogens**: These are chemicals that can increase the risk of cancer. Examples include substances like caffeine and nicotine, which are found in various beverages.
- **Radiation**: Certain types of radiation, such as X-rays and UV rays, can also be carcinogenic when there is excessive exposure.
...