Rectifier

A rectifier is a device that can convert Alternating current (AC) to Direct current (DC). This is a process called rectification. Many rectifiers in the 20th century were made of metals like copper, iron, and silver. Nowadays most are semiconductors.
"Half-wave rectifiers" only have one side of a waveform, while the "full-wave rectifiers" use both sides of a waveform. The left-hand side of the full-wave rectifier circuit consists of four diodes: a diode bridge. Half-wave current is a current that can only flow in alternate current, a full-wave current can flow both alternating current and direct current. 
Diode bridge is electrical circuit that consists of four diodes. It acts as a full wave rectifier to convert alternating current to direct current.