An electric current is a flow of charge. In a metal wire the charges that move are electrons. In direct current (d.c.) the charge moves in one direction only. It keeps moving the same way round the circuit for as long as the circuit is switched on.
Cells and batteries supply direct current. A battery is made of two or more cells joined together. One terminal is always positive and the other is always negative, so the current always flows the same way.
A torch, a toy car and a mobile phone all run from batteries, so the current in them is direct current. The size of a direct current can change, for example when a bulb is added to a circuit, but it never changes direction.