What are polar solvents and non polar solvents? And why polar solvents and the ions of ionic compounds have strong attractions.

When a covalent bond is formed between elements of different electronegativity, the electron shared is partially shifted towards the element of higher electronegativity and a slight negative charge and a slight positive charge develops on element of higher and lower electronegativity respectively. As a result, there is either a permanent separation of positive and negative charges, or the centers of positive and negative charges do not coincide.This creates a permanent dipole moment in molecule if the molecule doesn't has any other dipole nullifying the effect of former. The solutions having such characteristics are called polar solvent. For example water.
A solvent that does not have a permanent electric dipole moment and therefore has no tendency for intramolecular association with polar species are said to be non-polar.
The attraction between polar solvent and ions are similar to that between a simple dipole and a free charge.