Serial Communication between two Arduinos

Hi

I am trying to connect two arduinos using serial (TX and RX ) . The condition is for them to transmit at very high speed between the serial link.Does anyone has a written code to do this.

In this same project i would like implement multiplexing and de-multiplexing so if you have any ideas could you please help me out .

There are lots of examples of using serial comms. Have you looked at any of them?

In this same project i would like implement multiplexing and de-multiplexing so if you have any ideas could you please help me out .

Multiplexing of what? Analog signals? Digital signals?

The condition is for them to transmit at very high speed between the serial link.

Define "very high speed"!