Which is more appropriate — "I work for" or "I work at"?

If you are working as an employee at an organization, when you tell about it to others which usage would be more appropriate?

I work for company.

I work at company.

Or are both usages correct?

Solution 1:

Both usages are correct, and they mean the same thing.

The only minor wrinkle is that at can be used to refer to a physical location as well as a company itself:

I work at Microsoft.

I work at the Microsoft Redmond campus.

Whereas for cannot be used this way:

I work for Microsoft.

*I work for the Microsoft Redmond campus.

The last sentence would somehow indicate that you are employed by the campus itself, which probably isn't what you mean.

You work for a company at a location.

I work for Comcast.
I work at the Comcast building.