AwakeTooLong is correct in that Wicca was first formed in the 1930s. But it was not widely known at that time. Known only to the few who were initiated by Gardner. Wicca is based on old witchcraft beliefs, and was illegal until 1951. I first heard of Wicca around 1958-9. I bought Gardner's book "Witchcraft Today". In the 1960s I did get to meet some "Wiccans" (By the way, at that time it was Wica. Only one C).
So, although witchcraft, as I was trained, is very old, Wicca is less than a hundred years old. But it rapidly became popular once it became legal.
But there are now so many "paths", so many neo-Pagans, that the original Wicca is not the same as it was. I was taught by a witch, in the old ways. I get lost now in all the modern "sects".
I would explain Wicca as just another religion. When I have been asked (usually by Christians) to explain witchcraft, I ask them if they can explain Christianity. Most of them cannot!