Breadboarding: Connecting the TX Pin from a Microcontroller to the RX Pin of Another Microcontroller

For a microcontroller to be able to transmit, a wire must be connected to the TX pin of that microcontroller and this wire should be connected to the RX pin of the other device. To be able to receive data from another microcontroller or device, a wire must be connected to its RX pin. This wire should also be connected to the TX of the other microcontroller or device.