Polarity is defined as the charge difference between parts of an object. In this case, the object is a water molecule. Although the water molecule is neutral, the oxygen atom has a slightly negative charge, and the two hydrogen atoms both have a slightly positive charge. The molecule's bent shape puts the oxygen one one side and hydrogen on the other, allowing the oxygen side to attract positive charges and the hydrogen side to attract negative charges.
I'll use this water and this salt to show you guys an example. Polarity is the reason why water is such a good solvent. When the salt is put in the water, it looks as if it has completely disappeared. The negatively charged oxygen pulls the sodium cation, and the positively charged hydrogen pulls the chlorine anion. This pulls the salt molecule apart and makes it seem as if the salt is part of the water.
Mr. Tran: Again, what was the name of this property of water? Deniz: Surface tension, right? Mr. Tran: SHAKING MY HEAD, Deniz. SHAKING MY HEAD.