Vocabulary

Before we begin, here is some useful vocabulary that you will need

私・わたし – I or me (In Japanese, pronouns do not change form)
トム – Tom (name)
アメリカ人 – American
これ – This
りんご – Apple
学生・がくせい – Student
ロボット- Robot
車・くるま – Car

Basic Pattern – XがYだ。

A basic Japanese sentence is composed of a grammatical subject and a predicate where the subject of the sentence is the doer or agent and the predicate is a statement that we make about the subject. For example in the English sentence “Tom is American”, “Tom” is the subject and “American” is the predicate with the verb “to be” (conjugated as “is”) acting as the copula which is a linking verb that connects the subject to the predicate.

So in English, the pattern is “[Subject] is/am/are [Predicate]”. In Japanese, the equivalent is “[Subject] が [Predicate] だ”. So the Japanese version of our example sentence becomes トムがアメリカ人だ.

To understand the Japanese version completely, we need to look at the two grammatical words that appear in the Japanese sentence, alongside “Tom” and “American”, which are が and だ.

が belongs to a class of small grammatical words known as particles (助詞・じょし）. In Japanese, particles are used to express the relationship between words in a sentence, and the grammatical role that they play. All particles attach directly to the end of the word they are modifying, as suffixes.

The particle が marks the grammatical subject of a sentence. So in this case, since “Tom” is the subject, he is marked as such by attaching the particle が to the end of the word “Tom”.

The word だ at the end is the copula, comparable to the English “to be”. Unlike in English, where the copular “to be” conjugates for person into various forms such as “am”, “are”, “is”, etc, in Japanese, the copula stays だ irrespective of person. It also comes at the end of the sentence, instead of in the middle, as in English.

Examples

So let’s look at some more example sentences using the vocabulary from above：

わたしががくせいだ。 – I am a student.
これがりんごだ。- This is an apple.
わたしがロボットだ。 – I am a robot.
これがくるまだ。- This is a car.

As you can see, any two nouns can be substituted for the subject X and the predicate Y and the pattern remains exactly the same. Also keep in mind that Japanese does not have any articles such as a(n) or the, nor does it mark plurals. So you can just use がくせい or りんご to mean a student or an apple.

Subject Dropping

If these examples sound like a mouthful, no need to worry. In Japanese, it is perfectly grammatically acceptable to completely omit the topic/subject from the sentence if it is obvious from context what you are talking about. So the pattern XはYです can be simplified to just Yです. Let’s look how this affects the example sentences from above.

がくせいだ。 – (I) am a student.
りんごだ。– (This) is an apple.
ロボットだ。 – (I) am a robot.
くるまだ。– (This) is a car.

Although I kept the words (I) and (This) in the English translation, in reality, the subject can be anything. So ロボットだ can mean I am a robot or It is a robot or They are robots or anything else that is only determinable by context. This may seem confusing, but in practice it is usually pretty clear what people are talking about.