This chapter reviews one specific computer-based translator’s tool, i.e. the widely used translation memory. The idea is that the translator can consult a database of previous translations, looking for anything similar enough to the current sentence to be translated, and can then use the retrieved example as a model. The key to the process is efficient storage of the sentence in the database, and most importantly, an efficient matching scheme. This chapter looks at the different ways that a TM’s database can be built up, and at how the matching function works. It offers some suggestions about how a TM system can be evaluated. A brief discussion of the related technique of Example-based MT rounds off the chapter.