Particles · N5
は vs が: topic and focus
The central difference between two particles learners often translate as “subject”.
In short
は sets a topic or contrast; が identifies or highlights the participant tied most directly to the predicate.
How it works
私は学生です presents “as for me” and says something about that topic. 誰が来ましたか asks who came, so the answer 田中さんが来ました identifies the missing participant. In real conversation, context can make either particle natural for different information structure.
Useful contrast
This is not simply “は = subject” and “が = object”. Both can occur with English subjects, but they organize information differently.
Examples
私は学生です。
As for me, I am a student.
猫がいます。
There is a cat.
Common pitfall
Do not choose by translating word-for-word from English. Ask whether you are establishing a topic/contrast or identifying what satisfies the predicate.