A voltage divider is a circuit that produces an output voltage that is proportional to the input voltage. One typical configuration consists of a pair of resistors in series from the input voltage to ground, with the output voltage taken from the junction of the resistors. As an example two equal valued resistors will give an output voltage 50% of the input.

Detailed explanation for voltage divider.

Reoccurring questions

Once in a while a novice tries to use a voltage divider using voltage divider to lower a supply voltage. Here are the threads which explain why that's not a gooe enough idea.
When would I use a voltage regulator vs voltage divider?.
how to reduce DC voltage using resistors?