Each variant of the Raspberry Pi has a different Pi Revision Number. There have now been a number of revisions to the Raspberry Pi PCB so the device you have in front of you could be one of a number of variants. The changes include mounting holes, modifications to the power supply circuitry, different GPIO headers and varying numbers of USB ports. The Pi 2 and Pi 3 introduced new CPUs and additional memory.
Finding your Pi Revision Number is a useful technique to identify what model of Pi you have and, in some cases, where it was manufactured.Read More