character - technical definition

A letter (e.g., a,A, b, and B), number (0, 1, 2, or 3), punctuation mark (e.g., ;, :,`, or "), or other symbol (e.g., @, #, $, or %) or control code (e.g., carriage return (CR), line feed (LF), acknowledgement (ACK), or negative acknowledgement (NAK)) that can be represented by a single data byte. See also byte.