A WIFI extender is used to extend the coverage area your WIFI network. It works by receiving your existing WIFI signal, amplifying it and then transmitting to the boosted signal. Your signal strength and bandwidth will be immediately boosted and directed to the WIFI trouble spot.
Solutions can be simple plug in adaptors, moving to boosters built into your electrical system (where the range extending further for sheds or garden buildings). Most solutions can be up and running in a matter of hours with no changes to the existing household wiring.