http://nihonshock.com/2010/02/particles-the-difference-between-wa-and-ga/
Japanese has an interesting way of dealing with different areas of conversation. Unlike English which just has a grammatical subject and object, Japanese has added a topic. The topic is marked with the word “wa”. A sentence can have a topic and a subject. This can add nuance to a sentence with the addition of just one word. The equivalent in English would be a clunky “as for me”, or “while on the topic of”.
“Watashi no namae wa Shigeru desu” is how you say “My name is Shigeru” in Japanese. Literally translated, it means “As for my name, it is Shigeru”. The topic can refer to something already mentioned, so it is much easier to let people know that you are referring to something that was already in the conversation.
“Watashi wa gakusei desu” means “I am a student” but “Watashi ga gakusei desu” (ga being the subject marker) also means “I am a student”, but the interesting thing about “wa” is that it can be used to contrast with something someone already said. Someone would say “I am a university student” and you could reply “Watashi wa seito desu” (As in, oh now that we are talking about education, did you know that I am in high school”.
It is awesome to see how different languages can handle something so differently, and in this case come up with such an elegant solution to this problem. In Japanese, all you need to do is use the word “wa” and it has this whole other function that we don’t really have access to in English. This is why I find languages so fascinating.
