Research in Privacy Enhancing Technology has meanwhile a tradition of at least 20 years. One application (if not the most significant at the present) of Privacy Enhancing Technology is anonymous Web surfing. While weak protection can be achieved by simple proxy solutions, strong anonymity needs more effort: Systems like JAP and TOR are based on the idea of the "mix network" introduced by David Chaum in 1981. The talk presents selected basic privacy enhancing techniques, available practical solutions and gives some insights into the operation of the JAP Anonymizer.