Here's why:

* Oxygen is more electronegative: Oxygen has a stronger pull on electrons than hydrogen.

* Unequal sharing of electrons: This means the electrons in the O-H bonds spend more time closer to the oxygen atom, creating a partial negative charge on the oxygen side (δ-) and a partial positive charge on the hydrogen side (δ+).

This polarity makes water a great solvent and gives it many unique properties.