Definition of Cantilever:
a projecting beam or member supported at only one end: such as
a : a bracket-shaped member supporting a balcony or a cornice
b : either of the two beams or trusses that project from piers toward each other and that when joined directly or by a suspended connecting member form a span of a cantilever bridge
A Cantilever beam is supported at one end and carrying a load at the other end or distributed along the unsupported portion. The upper half of the thickness of such a beam is subjected to tensile stress, the lower half to compressive stress, tending to crush them. In building, any beam built into a wall and with the free end projecting forms a cantilever. Longer cantilevers are incorporated in a building when clear space is required below, with the cantilevers carrying a gallery, roof, canopy, runway for an overhead travelling crane, or part of a building above.
In many modern homes, the architect will design the appearance of a floating overhang or a floating fireplace. The perception is to create a visual, that defies physics. Herein lies the beauty of minimalistic modern architecture. When selecting an architect, review their work on-line and request these features to be incorporated in your home. It’s pretty magical.