Difference between “wa” and “ga”
Lots of people learning Japanese ask about the difference between the topic marker “wa” and the subject marker “ga”.
For example, “Watashi wa” and “Watashi ga” are different.
“ga”(が) is called a subject marker. Usually, the word in front of this marker is the subject of the sentence and the most important part, or a new information to the listener, of the sentence. In the sentence “Watashi ga Demi desu.”, “Watashi ga” is the most important. It is similar to “ I am Demi.”
On the other hand,
“wa”（は）is a topic marker. Topic of a sentence is sometimes the subject, but not always. It is just a topic. The speaker indicates that he/she is talking about it. “I” in the sentence “I am Demi.” is not that important and is just a topic. The most important part of this sentence is “Demi”. The speaker is introducing her name, in “I am Demi.”
There is no bold letters or CAPITAL letters in Japanese, so when something has to be stressed, subject marker “ga” is used.
