需 (w)

(xū) to require; to need; to want; necessity; need

需求 (w)

(xūqiú) requirement; demand (economics)

需要 (w)

(xūyào) to need; to want; to demand; to require; requirement; need

需要是发明之母 (w)

(xūyàoshìfāmíngzhīmǔ) Necessity is the mother of invention (European proverb).