Data acquisition is the processing of multiple electrical or electronic inputs from devices such as sensors, timers, relays, and solid-state circuits for the purpose of monitoring, analyzing and/or controlling systems and processes.  Data acquisition instrument types include computer boards, instruments or systems, dataloggers or recorders, chart recorders, input modules, output modules, and I/O modules.  Computer boards are self-contained printed circuit board with full data acquisition functionality; typically plugs into a backplane or motherboard, or otherwise interfaces directly with a computer bus.  Instruments or systems are fully packaged with input and output, user interface, communications capability, etc. They may include integral sensors.  Data loggers and data recorders are data acquisition units with instrument functionality with specific capability for data storage. May be for general purpose or application-specific data acquisition.  Chart recorders generate real-time plots, graphs or other visualizations of data.  Input modules are devices (module or card) configured to accept input of sensors, timers, switches, amplifiers, transistors, etc. for use in the data acquisition system.   Output modules are devices with specific functionality for output of amplified, conditioned, or digitized signal.  I/O modules have both input and output functionality. Digital or discrete I/O includes on-off signals used in communication, user interface, or control.