Hi Etsuko, In my opinion, juxtaposition is an uncommon word. It shows that something close together has opposite effect, contrast. It is a noun, but "to juxtapose" is also a verb. Dictionary: "the fact of two things being seen or placed close together with contrasting effect." Example sentence: "Happy dreams were often juxtaposed with nightmares." Hope this helps?

Nayan is correct in saying that "juxtaposition" is a fairly uncommon word. I think you'll more likely hear people say "a side-by-side comparison," which is exactly what it sounds like. It's taking two things, putting them next to each other (side-by-side), and comparing them to one another. If you want to use the word juxtaposition, here are some examples: "When juxtaposing the rich and poor, it is clear that they live very different lives." (In this sentence, you are not literally putting the rich and poor next to each other, but you are putting the ideas next to each other to compare them) "I juxtaposed the beige couch with the dark brown rug to make both pieces of furniture stand out."