Explain $\sigma$ bond formed by $s-s$,$s-p$ and $p-p$ overlapping.

(N/A) The covalent bond formed by the overlapping of atomic orbitals can be classified into two types:
$1$. $\sigma$-bond: This type of covalent bond is formed by the end-to-end (head-on) overlapping of two atomic orbitals along the internuclear axis. It is also known as axial overlapping.
$a$. $s-s$ overlapping: This involves the overlapping of two half-filled $s$-orbitals along the internuclear axis.
$b$. $s-p$ overlapping: This involves the overlapping between a half-filled $s$-orbital of one atom and a half-filled $p$-orbital of another atom along the internuclear axis.
$c$. $p-p$ overlapping: This involves the head-on overlapping of two half-filled $p$-orbitals along the internuclear axis.
$2$. $\pi$-bond: In this type of covalent bond formation,the axes of the overlapping atomic orbitals remain parallel to each other and perpendicular to the internuclear axis,resulting in lateral (side-wise) overlapping.