Did you just link together several memories of your brother to form one longer story for his wedding toast? If so, you concatenated without knowing it! That’s because concatenate means to link things together to form a series or chain.
In truth, the word concatenate is really a mouthful. It's hard to imagine anyone using it when they could use a synonym, such as link for the verb form and linked for the adjective form, just as well. But if you’re looking to impress with big words, try it out! To understand the situation in the Middle East, you have to concatenate the events of the past 50 years. You can tell others about that book you really love which is really a concatenate series of related poems.