Definition Of polar molecules and nonpolar molecules please?

Non polar molecules are symmetric with no unshared electrons. Polar molecules are asymmetric, either containing lone pairs of electrons on a central atom or having atoms with different electronegativities bonded.

Explanation:

When things are different at each end, we call them polar. Some molecules have positive and negative ends too, and when they do, we call them polar. If they don't, we call them non-polar. Things that are polar can attract and repel each other (opposite charges attract, alike charges repel).