Computer Assisted Translation, or Computer Aided Translation (or the acronym CAT) designates a form of translation where a human translator uses a specially developed software to facilitate and provide support to the process of translation. The programs for the management of translation memories store the source texts and the correspondent previously translated texts in a database, so that we can later retrieve and use the old translated text segments during the process of translation of a new  source text. The size of the database increases in parallel with the increase in the number of translations carried out using that memory. This means that, especially when dealing with technical texts, it is possible to retrieve previously translated sentences, words, or segments.


CAT Tools are obviously much less useful in the case of non-technical texts, in which the percentage of repetitions is little or virtually non-existent and the interpretation may vary. Consequently, it is evident that CAT Tools are not automatic translation programs, on the contrary they are very personalised and 'human', as memory databases are essentially constituted by the work of the translator.

In fact, alignment programs are used to align and adjust two documents (the source and the target) by dividing them into segments, in an attempt to determine which segments of the translated document are associated to the source document, in order to build a translation memory.