How a house is built
Posts you can see
A column carries load in compression. On this house the porch posts are the columns you can see.
Arrow keys turn the house. Plus and minus, or the zoom buttons, change the zoom. A horizontal drag turns it after you tap the drawing. Reset view returns to the step camera.
The drawing needs WebGL. The notes on the page still stand.
A column takes load from above and delivers it below, mostly in compression. How tall it is compared with its thickness, and how it is held at each end, decides whether it stays straight. A wall of studs is a row of small columns sharing the load.
The posts under the porch roof are the clear columns on this house. Each one needs a footing of its own, or a beam that reaches a footing. The sketch shows the posts. It does not size them or the footing.