What is the definition for causal condition?

A SYSTEM Iis said to be causal if the present valkue cof the output siugnal depends only on the present and past values of the input signal.examples of causal systems 1.y[n]=2(x[n]+x[n-1]+x[n-2]); 2.it is example of non causal system y[n]=x[n+1]; A system is said to be causal if the present value of the output signal depends only on the present and past values of the input signal.examples of causal systems 1.y[n]=2(x[n]+x[n-1]+x[n-2]); 2.it is example of non causal system y[n]=x[n+1];