Back in the Victorian era, it was thought that white would hide sweat the best while playing tennis, and that this would be the most proper. This tradition has lasted to this day, including socks, shoes, wristbands, headbands, hair accessories and sweaters. Even any off-white shades are prohibited. Only a 1 cm or half inch trim is allowed of colour.

Even if a player requires medical tape or a brace, it should be white in color wherever necessary.

Spectators however, do not have to wear white, but are often very well dressed.

More Info: www.wimbledon.com