The letters "c," "b," and "a" are the first three letters of the English alphabet. Each letter has its own unique sound and can represent different phonetic values in various words. For example, "c" can sound like /k/ in cat or /s/ in city. In addition to their phonetic roles, "c," "b," and "a" are often used in grading systems, where "A" represents excellent performance, "B" indicates good performance, and "C" signifies average performance. These letters are also commonly used in programming languages, such as C and BASIC, to denote different coding structures.