Before revision: The idea that the output of a function at any time depends only on the past and present values of input is defined by the property commonly referred to as causality.
After revision: A delta response system h(t) is said to be causal if and only if the output of system depends only on present or past time input of input signal x(t) or it can be said that a system is said to be causal if the value of h(t)=0 for all t<0.Edited:Mridul BhaskarThe idea that the output of a function at any time depends only on the past and present values of input is defined by the property commonly referred to as causality.