A data type is a classification that specifies which type of value a variable can hold in programming and data management. Common data types include integer, float, string, and boolean. Each type determines the kind of operations that can be performed on the data and how much memory it occupies. Understanding data types is essential for effective coding and data manipulation. For example, an integer can be used for counting, while a string is used for text. Choosing the correct data type helps prevent errors and optimizes performance in software applications and databases.