I saw some sentences using "on top of" while I was reading some book which was about ASP.NET Core (which is a Microsoft Web Development Framework). the sentences:

1-(MVC) It was created on top of the components for Web Forms.

2- Dot Net Core is built on top of the new dot net core framework.

I have searched for some definitions for "on top of something" and also for knowing that how to use this idiom in a sentence, but actually haven't realized what "on top of" mean here in these two sentences! So would anybody explain it to me please?

  • For this usage, simply regard it as synonymous with "on." Specifically, "positioned physically above and contacting ___": "The house is built on top of the foundation." Obviously, for .Net, it's used metaphorically: it's not literally positioned "on top of" a framework—but then it's not literally "built" either. Dec 14, 2021 at 19:50
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    Also, it's not really an idiom, just an idiomatic usage—I thought you were going to ask about the idiom "on top of it" which means in control of a situation. Dec 14, 2021 at 20:49
  • @AndyBonner can we say that the Earth was built on top of the water and land, according to your explanation? Dec 15, 2021 at 11:20
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    Sorry, your comment makes sense in response to Casey's answer, but not to my explanation. I left a comment rather than an answer because these are not unusual usages, but common dictionary definitions. Please edit your question to show that you have looked up "built," "on," and "top," and how those entries fail to answer your questions. "On top of X" does not mean "using X." It means "on." If it helps, add "the": "on the top of." The earth is not "on top of" anything, unless perhaps it is four elephants and the great turtle A'Tuin. Dec 15, 2021 at 13:44
  • Yes, I exactly know what you mean, but I just wanted you to help me know if I can use "on top of" in my response to Casey. I mean I just wanted to know whether to use "on top of" instead of "using" in that example I asked from Casey or not? Dec 15, 2021 at 14:07

1 Answer 1


This means that it was built using those other tools. The metaphor here is a physical building, which is built on top of some sort of foundation.

  • I think this is a good answer. So can we say that the Earth was built on top of the water and land, according to your explanation? Dec 14, 2021 at 20:50
  • Thanks for contributing! However, the continuing confusion (or is it trolling?) shows why it's good to wait for a question to meet our requirements before giving an answer instead of a comment. Dec 15, 2021 at 14:23
  • Thanks. So would you give me an example for where to use "on top of" in a sentence, please? Dec 15, 2021 at 16:12
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    @AndyBonner I've been on Stack Exchange for the better part of the decade and I honestly still don't really get what people want. Just a few weeks ago I was hearing moderators say comments were absolutely the wrong place for answers and never write one there.
    – Casey
    Dec 16, 2021 at 5:34
  • @HosseinDara No, that doesn't fit the metaphor. The water and dirt are components of the planet, not a foundation for them.
    – Casey
    Dec 16, 2021 at 5:35

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