What is a CAT tool, and why do translators use translation memory?

By the BF-Blessy team · Updated November 7, 2026 · 2 min read

CAT stands for computer-assisted translation. It does not mean that a machine translates for you and the human disappears. A CAT tool is a workspace that helps a human translator work faster, stay consistent and make fewer mistakes. If you translate documents, even as a side job, understanding three ideas will change how you work: segments, translation memory and glossaries.

Segments: working sentence by sentence

A CAT tool cuts a document into segments, usually one sentence each. The original is on one side and your translation on the other. You never lose your place, and the layout of the document is kept safe while you work on the words.

Translation memory: never translate the same sentence twice

Every segment you approve is saved with its translation in a translation memory. Later, if the same or a similar sentence appears, the tool shows you what you wrote before. In contracts, manuals and reports, many sentences repeat with small changes, so this saves a lot of time. It also keeps your wording the same from the first page to the last.

• Exact match: the sentence is identical. You can reuse the translation.
• Fuzzy match: the sentence is similar. You adjust the difference.

Glossary (termbase): the right word every time

A glossary stores the terms that must always be translated the same way: the name of a product, a medical term, a legal expression. When a segment contains a term from your glossary, the tool points it out. This matters for clients who care about consistency, such as companies, hospitals and organisations.

Machine suggestions: a help, not a replacement

Many tools can also offer a machine translation as a starting point. A professional treats it as a draft: read it, correct it and approve it. Machine translation is weaker for rare languages, idioms, humour and technical subjects, so your judgement stays essential.

Quality checks

A good tool can also check your work before you deliver: missing numbers, different links, repeated words, or a target that looks identical to the source. These checks catch small mistakes that tired eyes miss.

Who benefits

• Freelance translators who want to deliver faster and look more professional.
• Students learning translation who want to see how professionals work.
• Small organisations that translate the same type of documents again and again.

A first routine you can copy

1. Upload the document and let the tool cut it into segments.
2. Translate segment by segment, using suggestions only as drafts.
3. Save each approved segment so it enters the memory.
4. Add important terms to the glossary.
5. Run the quality check, fix what it finds, then export.