Alphanumeric characters are symbols that include both letters and numbers. Specifically, they consist of the 26 letters of the English alphabet (A-Z, both uppercase and lowercase) and the digits from 0 to 9. These characters are commonly used in various applications, such as passwords, usernames, and coding, to create a combination of letters and numbers. In addition to letters and numbers, alphanumeric characters can also include special symbols, depending on the context. For example, in computer programming or data entry, characters like @, #, and $ may be included to enhance security or functionality. Overall, alphanumeric characters are essential for effective communication in digital environments.