Continous Time Convolution

$$ y(t) = x(t) * h(t) = \int_{-\infin}^{\infin}x(\tau)h(t-\tau)\,d\tau $$

Discrete Time Convolution

$$ y[n] = x[n] * h[n] = \sum_{k=-\infin}^{\infin}x[k]h[n-k] $$