Perhaps the simplest explanation of lexicography is that it is a scholarly discipline that involves compiling, writing, or editing dictionaries. Lexicography is widely considered an independent scholarly discipline, though it is a subfield within linguistics.
Many consider lexicography to be divided into two related areas. The act of writing, or editing dictionaries is known as Practical Lexicography. The analysis or description of the vocabulary of a particular language, and the meaning that links certain words to others in a dictionary, is known as Theoretical Lexicography. Theoretical Lexicography is particularly concerned with developing theories regarding the structural and semantic relationships among words in the dictionary. Since it involves theoretical analysis of the lexicon, Theoretical Lexicography is also known as Metalexicography.
In order to better understand lexicography, it may help to know what a lexicon is. Lexicon is a term used in linguistics to indicate the archive of lexemes. Lexemes are abstract, minimal units in a language that link related forms of a word together. For example, the words fly, flight, flew, flying, and so on, are all morphologic variations of the lexeme fly. Fly is the lexeme because it is the base from which these word variations arise.