In a series circuit, if one part stops working, the whole circuit stops too.

This happens because the electricity has to pass through each part one after the other.

For example, if a light bulb goes out, the circuit breaks, and the flow of electricity stops.

On the other hand, in a parallel circuit, if one part fails, the other parts can still work.

Each part has its own path for the electricity to flow, so they aren't all connected like in a series circuit.

In parallel circuits, the overall resistance gets smaller, which is calculated like this:

$$\frac{1}{R_{total}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + \ldots$$

This shows that parallel circuits are more reliable because they keep working even if one part doesn’t.