This article aims at giving an overview of how CAT Tools work and is specifically intended for those translators who are familiarizing themselves with these tools for the first time. A CAT Tool is software whose functioning is based on the creation of a Translation Memory, which facilitates and speeds up the translator's work. After having briefly explained how the tools work, the advantages and disadvantages of their use are analyzed. Finally, suggestions are given for those who would like to know more about these tools and start using them.