There are 2 main reasons a fuse can blow. The first and more common reason is that it’s overloaded. Too many electrical appliances are plugged in, and cause the circuit to break and metal ribbon inside the fuse to melt. The result is that all the appliances powered by that circuit will suddenly go off. If this happens you can replace the fuse immediately, but a long-term solution would be distributing the electric load, i.e. moving appliances to other circuits.
Another reason is a short circuit. This usually occurs because of loose wiring, damaged wires along a circuit, or an internal wiring issue in an appliance. It’s also possible if wiring has been chewed through by a rodent. In this case, the short circuit must be fixed before the fuse is replaced.