what do we understand by polar and non polar (compunds or any other thing)
Polar molecules can be categorised as "polar covalent", "non-polar covalent", or "ionic".
A molecule is composed of one or more chemical bonds between molecular orbitals of different atoms. A molecule may be polar either as a result of polar bonds due to differences inelectronegativity as described above, or as a result of an asymmetric arrangement of nonpolar covalent bonds and non-bonding pairs of electrons known as a full molecular orbital.
Examples: H2O, NH3, sugars, etc.