What is an alpha character on a computer?

Excuse me, could you please clarify what exactly is meant by an "alpha character" on a computer? Is it referring to a specific type of letter or symbol that is used in computer programming, or is it perhaps a broader term that encompasses multiple types of characters? Could you provide some examples of alpha characters and explain their significance in the context of computer usage? I'm interested in understanding the distinction between alpha characters and other types of characters, such as numeric or special characters, and how they are used in different applications. Thank you.