White noise has a flat power spectrum — equal energy per Hz. It sounds like radio static. Used for: acoustic measurements (impulse response calculation), sound masking (privacy in open offices, tinnitus relief, sleep aid), and synthesis (creating wind, surf, and explosion effects).
White noise is perceived as bright/hissy because high frequencies have more Hz per octave (10,000–20,000 Hz has 10,000 Hz of bandwidth, while 20–40 Hz has only 20 Hz). Pink noise corrects for this by reducing energy 3 dB/octave, matching human hearing better.