Although Internet auctions have long been part of everyday life, they still operate within legal structures that were created for classic floor auctions. This thesis first shows the basics of the classic voluntary public auction. This is followed by an analysis of the special features of Internet auctions. In particular, it will be examined whether the standards for voluntary public auctions cover the special features of internet auctions and where there is a need for adaptation. The third part is dedicated to selected performance disorders in Internet auctions; particular attention is paid to the interaction between the participation contract of the platform operator and the auction conditions of the sellers.