Lexicography deals with everything that relates to the words. It is best to simplify that lexicography is the process of dictionary making.  

However, lexicography can be divided into two related disciplines :

•         Practical Lexicography - The art or craft of compiling, writing and editing dictionaries.

•        Theoretical Lexicography - The scholarly discipline of analyzing and describing the semantic,syntagmatic and paradigmatic relationships within the lexicon (vocabulary) of a language.

And lexicography is not only focus on English Language but also in other languages.

REFLECTION

Lexicography is describing the vocabulary of language. So, looking at the history of lexicography it is clear that dictionaries played an important role in making information available to the users. It does not only help the learners but also the native speakers because the language user relies on a dictionary as an authoritative source of information. 

A dictionary is not mainly as a reference book for different types of information on words such as pronunciation and meaning but it also can be a reference point for distinguishing the good or proper usage from the bad or wrong usage. Other than that, lexicography also helps to collect and compile a variety of words with same meaning (synonym) which known as Thesaurus. Hence, lexicography is important in order to define a right word with a right meaning.