A caffeinated drink is a beverage that contains caffeine, a natural stimulant most commonly found in coffee beans, tea leaves, cacao, and certain plants like guarana. These drinks are popular worldwide for their ability to increase alertness, reduce fatigue, and enhance mental focus. Common examples include coffee, tea, energy drinks, soft drinks like cola, and even some types of chocolate beverages. The caffeine content can vary significantly depending on the type of drink, preparation method, and serving size. While moderate consumption is generally safe for most adults, excessive intake can lead to side effects such as insomnia, increased heart rate, and nervousness.