In a parallel circuit, different components are connected on different branches of the wire. If you follow the circuit diagram from one side of the cell to the other, you can only pass through all the different components if you follow all the branches.
In a parallel circuit, if a lamp breaks or a component is disconnected from one parallel wire, the components on different branches keep working. Unlike a series circuit, the lamps stay bright if you add more lamps in parallel.
Parallel circuits are useful if you want everything to work, even if one component has failed. This is why our homes are wired up with parallel circuits.
When two components are connected in parallel, the current is shared between the components. The current is shared when it reaches the branches, then adds again where the branches meet.
In the diagram, 6 A flows through the cell. The circuit has three branches, each with an identical lamp, so 2 A flows through each one.
If the lamps were not identical, their resistances would be different and the current flowing through each lamp would not be the same. The greater the resistance of a lamp, the smaller the current that flows through it. The current would still be shared between them, and it would still add where the branches meet.