Here's why:

* Electronegativity: Oxygen is more electronegative than hydrogen. This means it has a stronger pull on shared electrons in the O-H bonds.

* Electron Distribution: The shared electrons spend more time around the oxygen atom, giving it a slightly negative charge.

* Polarity: This uneven distribution of charge creates a polar molecule, with the oxygen end being slightly negative (δ-) and the hydrogen ends being slightly positive (δ+).