What are World of Warcraft private severs

Private servers are operated by a company or a group of people who are not affiliated with Blizzard Entertainment. These servers do not have Blizzard support, and all technical aspects are handled by the admins' technicians.

Some private servers have a small charge, while others are free to play in. Private servers are generally less stable and prone to being abandoned when compared to the official servers, but some stable ones have existed for years with minor incidents.