Age restrictions are rules that limit access to certain activities, products, or services based on a person's age. These restrictions are often put in place to protect younger individuals from content or situations that may not be suitable for them, such as alcohol, tobacco, or video games with mature ratings. Governments and organizations typically enforce age restrictions to promote safety and well-being. For example, a person must be at least 21 years old to purchase alcohol in many countries, while movies may have ratings like PG-13 or R to indicate appropriate age levels for viewers.