I was wondering after using the word system which word is more appropriate to use in order to explain and give more details about it: "where" or "in which"?

I can observe that both words are used but should it be chosen according to the context or their usage overlaps and does not change meaning much if we prefer one to another.

Following examples were excerpted from Google search results:

We develop a mathematical analysis for the steady state performance of a system where voice calls and data packets are transmitted over the same ..

How can we create a political system where elected representatives care much less about winning the next election and instead ...

A parliamentary republic is a system in which a prime minister is the active head of the executive branch of government and also leader of the ...

A multi-party system is a system in which multiple political parties across the political spectrum run for national election, and all have the capacity to gain control of government offices, separately or in coalition.

2 Answers 2


I've seen tricky questions about this on English tests. It depends on the degree of formality.

In highly formal English (including English tests unless otherwise specified), "where" should only be used for a physical location. Since "in the system" isn't a physical location, you have to use "in which".

In general use, including business and technology, "where" and "in which" are used interchangeably.

In casual use, "in which" (or any preposition + 'which') sounds stilted and awkward and is normally avoided, so you have to use "where".


They will be understood if used interchageably, but in which speaks to the structure, and where speaks to the ideas.

Democracy is a system where each person has a vote in which they can express their opinion.

  • 1
    Are you saying that "Democracy is a system in which each person has a vote" is incorrect? If so why? If not, why did you give that example? Feb 24 at 12:30

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