alt.sex is a Usenet newsgroup – a discussion group within the Usenet network – relating to human sexual activity. It was popular in the 1990s. An October 1993 survey by Brian Reid reported an estimated worldwide readership for the alt.sex newsgroup of 3.3 million, that being 8% of the total Usenet readership, with 67% of all Usenet "nodes" carrying the group. At that time, alt.sex had an estimated traffic of 2,300 messages per month.