Corpus based lexicograpy shows us its practical importance and usage in everyday life and in language learning and teaching. In my thesis I examine the steps of dictionary making and the usage of internet corpora in lexicography, and the main criteria for editing dictionaries. Because lexicographers have access to a large collection of corpora, texts in electronic form, a computer corpus has the advantage of being searched rapidly and efficiently, for checking information or for seeking answers to specific matters. The original dictionaries and lexicons written by hand will stay useful, but if we want to gain information quickly and compare frequency of occurrences, or any measure of a lexeme, we will tend to use internet corpora.