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 is 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 traveling 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 online and request these features to be incorporated in your home. It’s pretty magical.