Pmod interface or Peripheral Module interface is an open standard defined by Digilent Inc in the Digilent Pmod™ Interface Specification for peripherals used with FPGAs or microcontrollers.
Several types of modules are available from simple push buttons to more complex modules with network interfaces, analog to digital converters or LCD displays. These modules can be used with a variety of FPGA or micro-controller development boards from different vendors. Pmods are not necessarily plug-and-play - software and configuration is required - but the hardware interface is pre-designed and modules can be quickly assembled with host boards for prototyping or evaluation purposes with no soldering required.
Pmods come in a standard 6-Pin interface with 4 signals, one ground and one power pin. Double and quad Pmods also exist. These duplicate the standard interface to allow more signals to pass through to the module.
Pmods are available from multiple vendors such as Digilent , Maxim Integrated, Analog Devices and a variety of hobby sites.