A modern religion
Wicca is a modern Pagan religion that emerged publicly in Britain in the 1950s, largely through the writing of Gerald Gardner. It draws on older folklore, ceremonial magic and romantic ideas about pre-Christian Europe, but it is not a surviving ancient religion, and honest Wiccan teachers say so.
What Wiccans generally share
Reverence for nature and its cycles; a sense of the divine as both feminine and masculine (or beyond gender); the marking of seasonal festivals and moon phases; and personal responsibility rather than an external authority telling you what to believe.
What varies enormously
Deity names, ritual structure, initiation, secrecy, group versus solitary practice, and whether magic is central at all. There is no single Wiccan scripture and no central church.