What is CAT Tool (Computer-Assisted Translation)?

A CAT (computer-assisted translation) tool is the workbench a professional translator uses. It splits content into segments, shows source and target side by side, and surrounds the editor with productivity aids: translation memory matches, termbase lookups, quality checks, and often machine translation suggestions. Keyboard-driven confirmation of segment after segment keeps throughput high, which is the economic point of the whole category.

The name is worth unpacking. Computer-assisted translation means a human translates with software support, as opposed to machine translation, where software produces the translation. A CAT tool may embed MT as one suggestion source, but the human stays in control of every segment.

Classic examples are desktop applications like memoQ and Trados; most modern TMS platforms ship a web-based CAT editor instead. For software localization the practical requirement is that the editor understands your placeholders and plural syntax, so a translator cannot accidentally break :name or an ICU plural block.