Who do you work for? Answer: I work for an agency.

In this sentence, "for" means you are working on behalf of or as part of the agency. It suggests that the agency employs you or you represent it while doing e-commerce-related work. So, it's not literal like "for you" (addressing the agency), and it doesn’t mean "of an agency" (ownership). Instead, it means you work for the benefit of or as an employee/representative of the agency. Example Explanation: - "I work in e-commerce for an agency." → You handle e-commerce tasks, and the agency is your employer or client. - "I work in e-commerce of an agency." → This is not correct English because "of" doesn’t fit this context.

This agency does e-commerce, selling things online. People work at the agency so the e-commerce goes well, orders are sent out, money is collected. "I work in e-commerce for an agency" means that this person is a part of that work force at that agency. There may be other groups at that agency doing other things, but this person works in the e-commerce department.

In this sentence, "for" means you are employed by or working on behalf of the agency. So, it literally means: "I work in e-commerce as an employee of the agency." It doesn't mean "of" here but rather indicates who you are working on behalf of.