What factors are used to determine whether a bond will be polar or nonpolar? and what factors are used to determine whether a molecule will be polar or nonpolar?

 Each atom has a different ability to draw 
electrons to itself when it shares electrons (that drawing ability is 
called Electronegativity). 

A polar covalent means that an atom is electronegative, and the electrons are shared, but not equally.

So, if a bond between two atoms share electrons equally, then it is nonpolar and not electronegative.

If a bond between two atoms aren't shared equally, then it is polar and electronegative. Ex.) A polar molecule is water.