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).

* Attraction: The positive end of one water molecule is attracted to the negative end of another water molecule. This attraction is called a hydrogen bond.

* Weak but Important: Hydrogen bonds are relatively weak compared to covalent bonds (the bonds within a water molecule), but they are still very important. They are responsible for many of water's unique properties, such as its high boiling point, surface tension, and ability to dissolve many substances.