Fire stopping is best defined as the sealing of any openings to prevent fire (including smoke and heat) from passing through multiple building compartments. The spread of a fire is contained by creating fire resisting compartments, which subdivide the building (vertically or horizontally). Buildings must ensure that any openings and gaps are fire stopped to restrict both lateral and vertical fire spread
THE WIKI FIRESTOP DEFINITION IS:
A firestop is a fire protection system made of various components used to seal openings and joints in fire-resistance rated wall or floor assemblies. For penetrating cables, these can also be called as Multi Cable Transits (MCTs). Firestops are designed to restore the continuous fire-resistance of wall or floor assemblies, impeding the spread of fire by filling the openings in them with fire-resistant materials.