Where The Party is at. Literally.
Today we study John Sensei's favorite particle. We are going to address で in two parts, the first today and the second on day 21. This is an amazing particle that has a couple of connected purposes but all comes together when you catch, not only the function, but the feeling of this amazing particle as well.
で marks the domain/limitation, whether it be the location of action (domain), physical or conceptual domain (such as “the software industry”, “America”, or “the pokemon world”), limiting/end points in time and other quantitative limitation, and points of change.
で can also be used after a noun to indicated where or when an action is taking place. This can be used at just about any location, event, or time as long as the focus of the sentence is on the location or time in which an action is happening. Note that で can only be used with time when で marks a point of change.
[I] will meet my friends in Japan.
にほんで ともだちと あいます。
[I] ate my lunch at the park.
Let's talk after six o'clock tonight.
ろくじ の あとで はなしましょう。
The Disappearing は. Sometimes Japanese people will omit the particle は because they feel it is too obvious to mention. If I said “Ate at the park” in Japanese, the listener is expected to assume it was me that ate at the park, not that random homeless guy who thinks he is Jesus. This can be hard to adapt to initially, but pay attention to this kind of topic ellipsis in native Japanese conversations to get the hang of it. If you are ever worried that people aren't following your Japanese when you speak or write, you can always re-contextualize the conversation by adding the topic + は even at the end of the sentence. That might help put things back in context for them.