When it comes to AC and DC voltage, AC stands for alternating current and DC stands for direct current.
AC represents a current that moves like a wave through an electrical circuit, first in one direction then in the opposite direction.
DC means that current flows in one direction through an electrical circuit only, the positive and negative sides of the circuit are always constant.
Electrical components are often rated for either AC or DC voltage, sometimes they can be rated for both as well. It is therefor critical that the components are connected to the correct voltage source when installing them as to not cause any damage to the component or the electrical installation.
To Recap
AC voltage moves like a wave and DC voltage moves like a direct line. AC stands for alternating current and DC stands for direct current. We can also think of the differences in these 2 voltages like water at the beach and water in a river. At the beach, similar to AC voltage the water current comes into the beach then away from the beach. In a river the water current is always flowing in one direction down the river, similar to DC voltage.
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