Supports are sacrificial structures a slicer generates beneath overhangs and bridges of a 3D print, temporarily holding up material that would otherwise sag or collapse, then removed after printing.
Supports are temporary, sacrificial structures printed alongside a 📝3D Printing part to hold up sections that have nothing solid beneath them. Because material-extrusion printers build a part layer by layer from the bottom up, each new layer needs an existing surface to rest on; supports provide that surface under overhangs and steep features, then are broken or dissolved away once printing finishes.
The need for supports is governed by the overhang angle, measured from vertical. Overhangs up to roughly 45° generally print unsupported, because each layer is offset only slightly and still rests partly on the one below. Beyond about 45°, the layer projects too far past its predecessor, and the unsupported material sags, curls, or fails without a structure beneath it.
Supports are usually generated as grid or line lattices, though many slicers offer tree-style supports that branch up to contact points while using less material and detaching more cleanly. Their density is adjustable: sparse supports save filament and snap off easily, while denser supports back delicate features more firmly at the cost of harder removal and possible surface scarring where they meet the part.