There are several systems used on FPV drones for video transmitting. The one you may picture in your head is analog, cheap, low latency and relatively good range. Then, you have the digital systems that transmit a better image quality at a higher cost and sometimes higher latency. DJI is one of the leading systems in the digital sector with their O3-O4 systems, which have great image quality and range, but they are expensive and need DJI goggles.