Hybridization is the process of intermixing two atomic orbitals of nearly the same energy levels to form the same set of hybridized orbitals of same energy levels.
A simple way of finding the hybridization is:
First, observe the atom
Then, count the number of atoms connected ( Do not count the bonds)
Count the number of lone pairs attached.
Add the number of atoms and lone pairs. If the sum is 4, then the atom is sp3. If the sum is 3, then the atom is sp2. If the sum is 2, then the atom is sp.