Why is hydrogen bonded important to the properties of water?

Answer 1

Hydrogen bonding happens because of the polarity of water: the hydrogen is slightly positive and the oxygen slightly negative. This imbalance of charge causes water molecules to be attracted to each other (remember, opposites attact!). This attraction results in the cohesion of water--water molecules attracted to or "sticking" to each other, and adhesion -- water molecules attracted to surfaces or "sticking" to surfaces.