Normals are just the direction that mesh components are facing, but they’re hugely important in computer graphics. They control how many tools behave and how our objects look.

To see which way your faces are pointing, turn on Face Orientation in the viewport overlays menu.

If you have some faces pointing the wrong way, be sure to recalculate them. This one step will solve many potential issues! The hotkey for it is Shift N, or you can use Alt N to bring up the entire normals menu.

The normals are also responsible for whether our object looks smooth or faceted. You can switch between the two display types using the right click context menu in Object Mode even though it really is a property of the mesh data. Auto Smooth (or Smooth by Angle) can be used to make the faces smooth but appear split at sharp edges.