What is the full form of DC?

DC stands for "Direct Current".

It is the electrical charge that has the directional flow. The direct current flows within the same direction, this distinguishes it from Alternating Current (AC). Both the terms are used for the type of Galvanic Current.

The most common example of a direct current is the electrochemical cell. The promising feature it has is that it flows through conductors, but it can also flow through semiconductors, insulators even through the vacuum in the form of electron or ion beam as well.

Tracing back the history, though the discovery of the current took place during the period of 1800s the nature of the current was not discovered for a very long time. Later, a French physicist made a revelation that the current travels in one direction from positive to negative. When French instrument maker Hippolyte Pixii built the first dynamo electric generator in 1832, he found that as the magnet used passed the loops of wire each half turn, it caused the flow of electricity to reverse, generating an alternating current. The late 1870s and early 1880s saw electricity starting to be generated at power stations. These were initially set up to power arc lighting (a popular type of street lighting) running on very high voltage (usually higher than 3000 volts) direct current or alternating current.