Loop Cut
Add an edge loop around a mesh
Also known as: Blender loop cut · Blender Ctrl R · Loop Cut and Slide · Blender add edge loop
Definition
A loop cut adds a new loop of edges around a mesh, running across quads. In Blender press Ctrl+R in Edit Mode, hover over the mesh to preview the loop, scroll to add several loops, click to confirm and then move the mouse to slide it, with a right-click to keep it centered. Loop cuts add the extra geometry needed for details, sharper edges under Subdivision and control of shape.
In production
Loop cuts only work well on clean quads: a loop stops at triangles, n-gons and poles, so topology matters. Use them to add support loops near edges that should stay sharp under a subdivision surface, and to add detail only where it is needed. Press Alt and scroll to change the loop tool options, and use Edge Slide to fine-tune the position afterwards.