Generally, this is called Computer Assisted Translation, or Computer Aided Translation (both abbreviated to CAT), to define all the systems in which a translator uses specific computer programs as an aid to the translation process.
In the most common sense used by professionals, the term CAT tool, simply CAT refers to a subset of CAT programs proper: the one that includes programs for translation with the aid of memories.
In other words, a memory is nothing more than a database, whose registers made up of fragments of an original text with the corresponding translations, together with a series of attributes. These attributes can be mandatory (such as creation date), or optional (creator name, auditor name, etc.). The text units called segments correspond to the individual phrases.
Some authors prefer to speak of the Translation Environment Tool (abbreviated to TEnT), a term coined to better reflect the current state of translation programs, which group together several functions that go far beyond the simple management of translation memories. Current translation programmes offer terminology management, text analysis, spelling correction, project management and much more.
Advantages of a CAT tool
The typical advantages of translation memories and CAT tools for a professional translator are many:
The risk of leaving parts untranslated is minimized, as CAT tools do not allow the presence of segments with no target text.
It improves the uniformity of both internal and external text (if you work on more than one document); CAT tools always return the same translation for each identical source text.
Productivity is increased (the number of words translated in a given period), as Identical segments (also called 100% matches) are translated once, while similar segments (so-called fuzzy matches) are partially translated by the program.
This last advantage is particularly evident when translating the second version of a document in which most of the content remains unchanged.