How does the inset to create a cut works?

posted to: Modeling the Sides
What I don't understand is, if I move the vertices on the x axis and then extrude them on the opposite direction, how does that create a cut? Wouldn't that just create new vertices that sits on top where the old vertices were? 
  • spikeyxxx replied

    Well, he Insets twice, so exagerated, this happens:

    Inset.1.png

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