What is null modem cable and what is often used for?

A null modem cable is a type of serial cable that connects two devices directly, allowing them to communicate without a modem. It typically links two computers or devices by crossing the transmit and receive lines, enabling data transfer between them. Null modem cables are often used for direct device-to-device communication in applications like data transfer, programming embedded systems, or connecting older hardware that relies on serial communication protocols.