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. 
References[change | change source]
- "What is a Rectifier Circuit?". Michael Lemmon. 2009-02-01. http://www.nd.edu/~lemmon/courses/ee224/web-manual/web-manual/lab8b/node6.html. Retrieved 20 May 2012.
- Patrick Hoppe. "Half-Wave Rectifier". http://www.wisc-online.com/objects/ViewObject.aspx?ID=SSE402. Retrieved 20 May 2012.