A symbol is an object which represents something other than itself.
An alphabet is a set of letters or symbols in a fixed order, used to represent the basic sounds of a language.
An abbreviations is a letter(s) or shortened word used instead of a full word or phrase
A short form of a word or phrase, e.g. in addresses, Rd is an abbreviation of Road.
English uses 26 letters: ABCDEFGHIJKLMNOPQRSTUVWXYZ
BCDFGHJKLMNPQRSTVWXYZ are consonants.