'''Virtual Instrument Software Architecture''', commonly known as '''VISA''', is a widely used [[Input/output|I/O]] [[Application programming interface|API]] in the Testtest &and Measurementmeasurement (T&M) industry for communicating with [[Measuring instrument|instruments]] from a [[Personal computer|PC.]] VISA is an [[Technical standard|industry standard]] implemented by several T&M (Test & Measurement) companies, such as [[Rohde & Schwarz]], [[Agilent|Agilent Technologies]], [[National Instruments]], [[Tektronix]] and [[Kikusui]].
The VISA standard<ref name="VISA Specification">{{cite news |url=http://www.ivifoundation.org/specifications/default.aspx
|publisher=IVI Foundation |title=VISA Specification}}</ref> includes specifications for communication with resources (usually, but not always, instruments) over T&M(Test and Measurement)-specific I/O interfaces such as [[GPIB]] and [[VXI|VXI.]] There are also some specifications for T&M-specific [[Protocol (computing)|protocols]] over PC-standard I/O, such as VXI-11 (over [[TCPIP|TCP/IP]]) and USBTMC<ref name="USB Test & Measurement Class Specification">{{cite news |url=http://www.usb.org/developers/devclass_docs
|publisher=USB Implementers Forum Inc. |title=USB Test & Measurement Class Specification}}</ref> (over [[USB]]).
