Difference between で and だ?

[laser2302]

What's the relationship between で and だ? I heard だ is simpler form of で, can anyone please explain? And in what kind of situations we use で and だ?

For example in the following sentence で is used instead of だ:
私は 日本人 ではありません

Thanks!

 

[FinancialWar]

de is the te form of desu.

 

[Angel Valis]

What's the relationship between で and だ? I heard だ is simpler form of で, can anyone please explain? And in what kind of situations we use で and だ?

For example in the following sentence で is used instead of だ:
私は 日本人 ではありません

だ can be the short form of です.
で can be the conjunctive form of だ, meaning "and". e.g. 私は怠け者で恥ずかしい。(I'm lazy and shy)

ではありません is the negative (oft-written) long form of です. (The oft-spoken variant is じゃありません).

So in your example:
私は日本人ではありません。
You're saying that you're not Japanese.

If you wanted to say that you are Japanese, then you would say:
私は日本人です。

The more casual forms would be:
私は日本人だ。"I am Japanese"
私は日本人ではない。 "I am not Japanese"

In both negative examples, you can replace "では" with "じゃ" to make them sound a bit more natural in speech:
私は日本人じゃありません。
私は日本人じゃない。