[AmgedIsmail]

OK,
hello,
Is (ga が) also used as a Subject marker?
I noticed it in a website..
Sakura ga saita.
さくらがさいた。
Means: Cherry blossoms bloomed.
Shouldn't it be like:
Sakura wa saita.
さくらはさいた。

And you say (wa は) is not required to make a sentence.
So, you mean that subject is not always mentioned in a sentence??