JTAG is a common interface used for programming and debugging microprocessors and other types of embedded devices.
Joint Test Action Group (JTAG) is the common name for what was later standardized as the IEEE 1149.1 Standard Test Access Port and Boundary-Scan Architecture.
It was initially devised for testing printed circuit boards using boundary scan and is still widely used for this application. Today JTAG is also widely used for microprocessor debug ports.
With appropriate development tools and software, a developer can use JTAG to perform debugging operations like single-stepping, setting breakpoints, etc.
