Here's why:

* Polarity: Water molecules are polar, meaning they have a slightly positive end (the hydrogen atoms) and a slightly negative end (the oxygen atom). This polarity arises due to the unequal sharing of electrons between oxygen and hydrogen.

* Attraction: The slightly positive hydrogen atom of one water molecule is attracted to the slightly negative oxygen atom of another water molecule.

* Weak Bond: This attraction is called a hydrogen bond and is weaker than the covalent bonds within a water molecule, but still plays a significant role in water's properties.

These hydrogen bonds are responsible for many of water's unique properties, such as its high boiling point, surface tension, and ability to act as a solvent.