“Desu”「です」 is a tricky word.
It is one of the first words that most Japanese language students encounter, yet it is also one of the most misunderstood. Far too many people are mistakenly led to believe that it just makes a sentence polite, and although that is effectively all it does in some cases, it is so much more than that.
The truth is that much of the time, “desu” is actually a verb.
In simple terms, “desu” is the copula verb “to be” or “is”. It is the verb that links together two nouns, or a noun and an adjective, as being equal: A = B. Typically, this will be done using the pattern:
A wa B desu.
In polite Japanese, “desu” can almost always be interpreted this way, but it can be much more confusing once we deviate from simple polite sentences. This is because the informal equivalent of “desu” takes different forms depending on the situation.
To truly understand “desu”「です」, we need to take a close look at what role it plays in different situations.
Understanding the role of “desu”「です」 will make it much easier to determine when we should (and shouldn’t) use it, and in what form.
Perhaps more importantly, a proper understanding of “desu”「です」 will also give us a more complete picture of Japanese grammar and sentence structure as a whole.
In this article, I’m going to explore in depth the practical uses of “desu”「です」 and its underlying purpose in different situations.
By the end, you should have a fairly clear understanding of what “desu”「です」 is, when you should use it, and, perhaps most importantly, how it fits into the overall Japanese grammar system.