Anything about rectifier diodes (often just called "rectifiers" or "diodes"), a particular type of semiconductor diode.
Rectifier diodes are the most common kind of PN-junction diode. They are designed to behave as a unidirectional device, i.e. they let current flow just in one direction (from anode to cathode).
Most often when people speaks of "diodes" (without further specification or context) they refer to semiconductor rectifier diodes.
