interjection
A casual parting phrase, often used alone or with また. Implies a sense of 'in that case, goodbye'.
じゃ、またね。では！
Well, see you. Bye then!
expression
Compound of particles で (location/instrument) and は (topic/contrast). Marks a location, means, or method while implying a contrast with other possibilities. Often part of a larger phrase.
日本では、お正月に餅を食べます。
In Japan, we eat mochi on New Year's.
この問題は、普通の方法では解決できない。
This problem cannot be solved by ordinary methods.