What is the difference between usage of inside and on the inside?

For instance is there any difference in the following phrases:

  1. condensation on the  inside of the window
  2. condensation                inside the window

Maybe there are some situations where I can’t interchange them?


Brain comments helps a lot to understand the difference. I'll add one more example for clarification, please correct me if I'm wrong.

  1. Cameras will be on the inside the room
  2. Cameras will be inside the room

First example means that cameras are going to be fixed on the walls inside the room, the second tells that they are going to be inside rooms, but can be just standing on a leg.

  • Why would you use of at all in number two?
    – tchrist
    Commented Apr 5, 2015 at 18:56
  • Some thing have an "inner" suface—a window pane, for example, has a surface that faces outward, and a surface that faces inward. They have an inside (ie, the "in" side) and an outside (ie, the "out" side). So it makes sense to say the inside of a window. Other things (e.g. an apple) have an "inside" that is entirely contained in the thing. The inside of an apple is everything but the skin. With a person, one speaks of "insides" (plural) as meaning one's guts, or all internal organs. Commented Apr 6, 2015 at 3:12
  • As for the double-pane window I mentioned in a comment below (or triple-pane windows), we really don't have a good non-technical term for the space(s) between the panes, other than gap(s) , which doesn't really describe it. Commented Apr 6, 2015 at 3:19
  • @BrianHitchcock thanks for clarification. Could you please check my update in question and say if I understood it correctly? Commented Apr 6, 2015 at 8:25
  • Not quite. For the first "camera" example, if they are fixed to the walls, you would say they are mounted on the walls of the room. "room" is different from "window"—a room doesn't have an "outside", and "inside of the room" does not imply "on the walls". The second "camera" sentence could be more simply put: Cameras will be in the room. Commented Apr 7, 2015 at 8:13

1 Answer 1


"Inside of the window" refers to an interior space. "On the inside of the window" refers to an interior surface.

  • 2
    To clarify: it's a real problem if you get condensation inside a double-pane window, because you cannot get rid of it! Commented Apr 6, 2015 at 1:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.