でParticles: where, when and who
で: how and where it happens
で marks the setting or the tool: where something happens, what you use, why it happened, and when it ends.
Four jobs
One idea: “by way of this”
I study at the library.
Where an action happens
I go to school by bus.
What you use: a tool, a way of doing it, or a material
I stayed home with a cold.
A cause you can't control
This shop closes at the end of this month.
The point at which something ends
Action or existence?
で vs. に
I sleep in my room.
Something happens there, so で.
I'm in my room.
Something's simply there, so に.
Using something
で for tools, materials and costs
I eat with chopsticks.
Let's talk in Japanese.
I made a desk out of wood.
I bought it for 3,000 yen.
It'll be done in an hour.
How long it takes.
Controllable or not?
That's the difference between using and causing
The house collapsed because of the earthquake.
No one chose this, so で marks the cause.
I make bread with flour.
You chose this, so で marks what's used.
Watch out
Some other で-looking things
で can also be the joining form of です: 学生で、二十歳です, “They're a student, and twenty.” And でも (even) is its own word, though で + も also happens, as in 東京でも, “in Tokyo too”.
何で is ambiguous: it can mean “by what means?” or “why?” Use どうして or なぜ when “why” needs to be clear.
Check yourself
What is で doing here?
Your turn
に or で?
I live in Tokyo.
Say it yourself
Getting to work
A coworker asks how you get to work, and where you eat lunch.
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