Causal iir filter

1. Can IIR filter be causal?
2. What is a causal and non causal filter?
3. Are FIR filters causal?

Can IIR filter be causal?

(v) An IIR filter is linear and time-invariant. (vi) It is causal.

What is a causal and non causal filter?

A filter is said to be causal if its output depends only on present and past inputs. Conversely, non-causal filters depend also on future inputs.

Are FIR filters causal?

In all cases, the ROC includes the unit circle, i.e., FIR filters are always stable (but not necessarily causal).