App note from Nexperia presenting simple load switches in mobile and computing applications. Link here (PDF)
There are several reasons why a circuit or subsystem is required to be disconnected from the power supply using a load switch. A very simple and very common reason is that it helps saving power. An unpowered subsystem can eliminate power consumption due to leakage or standby currents. In portable electronic devices, load switches can be used to prevent damage from electrical surges, incorrect battery insertion and other damaging events that can enter through the power source.