What is the study of letters and letter combinations known as?

The study of letters and letter combinations is known as orthography. Orthography focuses on the conventional spelling system of a language, which includes rules about how letters and combinations of letters represent sounds and how they are arranged in written form. This field encompasses the study of spelling, punctuation, and the use of diacritics.

Phonographemics, while related to the representation of sounds through letters, is not the standard term used to describe the broader study of letters and spelling conventions in a language. Graphology, on the other hand, refers to the analysis of handwriting and is concerned with the psychological aspects of how people write, rather than the formal study of letters. Phonology focuses on the sound systems of languages, including how sounds are organized and function, but does not deal directly with the letters themselves.