An electrical circuit is a loop that electricity flows up from the battery. The conductor material allows electricity into it, examples of conductors are copper, gold and silver. In a parallel circuit the current gets split up into different branches. They can have bulbs, motors, buzzers in circuits. If one of the bulbs stop working there is still another one that could still work.
Bulbs in a parallel circuit are brighter than the same bulbs connected in a series circuit.
Here is how voltage and current behave in each arrangement to cause this difference in brightness:
