Simplest crystal is to be studied in cubic system. Three types of cubic systems are following:-

$\left(\mathrm{a}\right)$ Simple Cubic$\left(\mathrm{SC}\right)$ : Atoms are arranged at the corners of the cube.

$\left(\mathrm{b}\right)$ Body Centered Cubic $\left(\mathrm{BCC}\right)$ : Atoms are arranged at the corners and at the centre of the cube.

$\left(\mathrm{c}\right)$ Face Centered Cubic $\left(\mathrm{FCC}\right)$ : Atoms are arranged at the corners and at centered of the each faces.

Hence, in the face centered unit cell, the lattice points are present at the corners and the face centres of the unit cell.