what are the difference between は and が?

How to use these particles? It's a little confusing whether to use は or が

 

This what i know, 
は used when we want to talk about something, in this case we want to talk about "yumiko san"
ゆみこさんは　がくせい　です

が used when we have new information, and we want to report that news to the other, in this case there's a student who find a mouse and telling what he/she found to the teacher. 
先生、つくえの　下に　ねずみが　あります

I

I do not think thats correct, if the mouse would be know you still would use ga.

Obviously there is a mouse seems like new information, but so would gakusei be new information, why else would you mention it?

But i think you would be understood everywhere if you switched them and used them incorrectly...

But yes ga and wa letter get a lot more difficult, i think its better to focus on all the rest and later come back to that topic.

Its not only difficult to adequately explain it, but you probably will not understant it or forget it later. Better learn it in context, Japanese has a lot of things were even foreigners can easily spot patterns that you intuitivley later understand even if you cant conciously mention them.

 

 

は　= subject/topic

が　= (direct) object (and many other uses).

Example: せんせい　は　わたしのこと　が　すき　です。

Edit: After thinking about it today, I don't think I'm able to explain. I'm not a happy with the answer I posted yesterday. I think it might be better to learn it by heart. Meaning practicing reading, translating and writing a lot of sentences.

When I first started studying Japanese, I asked my Japanese friend this exact same question. She was confused, and it was only later that I understood why - it's because it entirely depends on context and grammar.

 

は is a "topic marker", as in 私は～　（わたしは～）. It  marks what the sentence is about. For example, in English, if I wanted to say, "My cat is black", "my cat" is the topic. It's the same in Japanese. 私のねこはくろいです　"My cat is black". Most of the time, this is how は is used. I suggest that you focus on getting used to this use.

が is a lot tricker because it has a variety of uses. が, at its most basic, expresses the existence of something. In English, it'd be similar to "is", or any word that expresses a state of being. For example,  ねこがいます。"There is a cat". くるまがあります。"There is a car". Basically, が is used when explaining that something exists, or asking whether or not something exists, be it an object, and event, a desire, or a feeling. 

 

All in all, you should view は as the marker for a topic (if you want to know what the sentence is about, look for the first は）Be careful, because は as a particle is pronounced "wa", while は anywhere else is pronounced "ha".

 

が, on the other hand, expresses various things, but most importantly, it expresses a state of existence of something. English equivalent would be "is" or "there is" (literally - "it exists"). 

OmniUO wrote today at 11:23 AM

When I first started studying Japanese, I asked my Japanese friend this exact same question. She was confused, and it was only later that I understood why - it's because it entirely depends on context and grammar.

 

は is a "topic marker", as in 私は～　（わたしは～）. It  marks what the sentence is about. For example, in English, if I wanted to say, "My cat is black", "my cat" is the topic. It's the same in Japanese. 私のねこはくろいです　"My cat is black". Most of the time, this is how は is used. I suggest that you focus on getting used to this use.

が is a lot tricker because it has a variety of uses. が, at its most basic, expresses the existence of something. In English, it'd be similar to "is", or any word that expresses a state of being. For example,  ねこがいます。"There is a cat". くるまがあります。"There is a car". Basically, が is used when explaining that something exists, or asking whether or not something exists, be it an object, and event, a desire, or a feeling. 

 

All in all, you should view は as the marker for a topic (if you want to know what the sentence is about, look for the first は）Be careful, because は as a particle is pronounced "wa", while は anywhere else is pronounced "ha".

 

が, on the other hand, expresses various things, but most importantly, it expresses a state of existence of something. English equivalent would be "is" or "there is" (literally - "it exists"). 

Thank you : this is very clear :-)