Let $\varphi(z)\sim\sum_{-\infty}^\infty a_kz^k$ be a bounded measurable function on the unit circle {\bf T}, where $a_k$ is the $k$-th Fourier coefficient of $\varphi$. Let $M_\varphi$ denotes the operator of mutiplication by $\varphi$ on the space $L^2(\mbox{\bf T}})$, the space of square integrable functions on {\bf T}. Given positive integers $m,n$, the operator $S_\varphi(m,n)$ is called a {\em sampling operator} on $L^2(\mbox{\bf T}})$ with symbol $\varphi$ if its matrix with respect to the standard basis $\{z^k:k\in\mbox{\bf Z}\}$ is given by $(a_{mi-nj})$ ($i,j\in\mbox{\bf Z}$). Basically, the matrix of $S_\varphi(m,n)$ can be obtained by "keeping" the entries of every $m$-th row and every $n$-th column of the doubly infinite Toeplitz matrix $(a_{i-j})$ while eliminating all others. In this talk we will consider some of the sampling operator's basic properties such as norm and its relation with the interpolation scheme in approximation theory.