For commercial use today, sodium is extracted from a combination of molten sodium chloride and calcium chloride through the Down's process. This is an electrolysis process in which an electric current goes through this molten mixture in a container with compartments to separate the sodium from the chlorine.
The way the Down's process works is that sodium ions, which have positive charges, collect at the compartment side that has a cathode. A cathode is a negatively charged electrode. The sodium moves up through the compartment and flows through a pipe. Similarly, chlorine ions, which are negatively charged, gravitate towards the anode side to form chlorine gas.
In this process, calcium is also separated and collected at the cathode side. The reason to include calcium chloride in this process is to lower the melting point of sodium chloride, which facilitates the separation of sodium and chlorine.
The first isolation of sodium occurred in 1807 when Humphry Davy extracted it from sodium hydroxide through the electrolysis process. Sodium is an alkali metal that is not found in pure form in nature.