What is polar?

Want to understand polarity , we must understand the word electronegativity first.

Electronegativity is the tendency of an atom to attract the bond pair of electron to itself.
The value of electronegativity is determined by its effective nuclear charge.

Polarity refers to a chemical covalent bond , in which, the BONDED pair of electron is under a different attraction towards the two atom in a bond, resulted in a displacement of the bond pair of electron to the atom which can exert a greater attraction force to the bond pair. This phenomenon is existed owing to a difference of electronegativity of the atom in a bond.

For example, O-H bond in water is in this case. Oxygen has a greater effective nuclear charge. (Because it has more proton and the screening effect is not stong.) So, it has a greater electronegativity compared to H. Thus, bond pair displace itself towards the oxygen atom, so oxygen atom will be likely to have partial negative charge ( seems to have more electron) and hydrogen..partial positive charge. This gives an ionic character to the O-H bond...and it will have pole as magnet. The negative charge oxygen will attract other positive charge things and vice versa.

This topic is covalent bonding, intermolecualr bonding and intermolecular force in AL syllabus.
AL syllabus include:
PHYSICAL
1) foundation..atom, molecule, and quantitative analyze
2) Atomic structure of discrete orbit and subshell
3) Thermodynamics
4) BONDING (your question is in this category)
5) Kinetics (rate of reaction)
6) Equilibrium, general, acid-base, redox
ORGANIC:
1) foundation knowledge to hybridization, isomer and reaction mechanisms
2) Organic base and acids
3) Structural characteristics of organic compound include alkane alkene benzene halogeno-compund, aldehydes, ketones, carboxylic acids and derivatives, organic redox
4) Chemical structure determination
5) Chem in action--> polymer drug and green chemistry
INORGANIC:
1) foundation in atomic structure and the reaction of atomic oxides to water
2) S-block (group 1&2)
3)P-block (group 7 and group 4)
4) d-block ( transition metal)

polar molecules have the difference in electronegatiivity ithat is greater than 0.4..
there is a uneven share of electrons within a covalent bond.
oxygen is highly electronegative.