Abstract This thesis handles special translation software, the mastery of which is becoming one of the basic requirements of successful translation work. The theoretical part describes the historical development, classification and main functions of translation memory systems. The thesis will further attempt to determine the criteria for the effective use of CAT tools and explore the text types and sorts for which the translation memory systems are most commonly used in the translation process. The functional view of the language-based text typology and the principles on which the translation memory systems work will also be handled. The practical part compares the result of a translation process (translation as a product) with and without CAT tools. The corpus of parallel texts (original translation) will be subjected to a translation analysis. This analysis concludes the levels which are affected by differences between translations made with and without CAT tools. The differences in the actual translation process with and without CAT tools which are not empirically verifiable will be analysed based on a survey conducted amongst translators. Then, the empirical part of the findings are summarized and systemized. The last chapter deals with the expected development in the translation market, the...