Voltage is very important for how electrical devices work. It acts like a force that pushes electric current through a circuit.

So, what is voltage?

Think of it as the measure of electric energy difference between two points. When we plug in a device to a power source, the voltage gives the energy needed to move tiny particles called electrons through wires. This movement is necessary for the device to work.

Here are a few key points about voltage:

1. Current Flow: Voltage is connected to current (which we can call $I$) through something called Ohm's Law. This law tells us that if we can remember $V = IR$, where $V$ is voltage, $I$ is current, and $R$ is resistance. This means that when the voltage is higher, we can have a higher current if the resistance stays the same.

2. Power Supply: Different devices need certain voltage levels to work properly. For example, in most homes, an outlet usually gives out 120 volts or 240 volts, depending on where you live. If you try to use a device with the wrong voltage, it might stop working or get damaged.

3. Resistance Effect: The amount of current that flows through a device can also depend on its internal resistance. If there is higher resistance with the same voltage, it results in lower current. This can affect how well the device performs.

In short, voltage is key for deciding how much current can flow in a circuit. It also plays a big role in how much power devices can use and interacts with resistance to affect how electrical systems function.