A bartender is a skilled professional who prepares and serves alcoholic and non-alcoholic beverages to customers in a bar, pub, nightclub, or restaurant. They must be knowledgeable about different types of drinks and be able to mix and serve them with precision and efficiency. 

The responsibilities of a bartender include taking orders, preparing drinks, maintaining inventory and the cleanliness of the bar, and handling cash transactions. They must also monitor customer behavior and prevent overconsumption of alcohol or any inappropriate behavior.

Prerequisites for becoming a bartender include excellent communication and customer service skills, knowledge of different types of drinks, and mixing techniques.