Luciano ES - The use of computers and all available paraphernalia by professional translators to achieve more speed, accuracy and overall efficiency in the translation of text from any language to another one or several other languages. That often involves the concept of translation memory, whereby the software "remembers" previously translated corpora and "suggests" the same translation to new corpus that matches a certain degree of similarity to the corpora stored in its database.
It's just a tool in the hands of a skilled professional, who does the actual work. It's different from machine translation, that (at least in theory) is software armed with enough vocabulary and "understanding" of grammar so it does not require similar corpora in a database or user intervention to produce the final version of translated text.
Computer-assisted translation is a very present reality, while machine translation still is very immature technology.
The most notable examples of computer-assisted translation programs are Trados [L1 ], DéjàVu [L2 ] and Wordfast [L3 ]. The corporate market that buys translation services relies heavily on Windows for its communication and data management needs, so these programs are all Windows-based. In other words, they handle MS Office documents.