Currently there is no defined standard or community agreement about unique and persitent identifers for museum objects on the internet. Persistent identfiers used in other domains have a different scope, are not suitable to identify real-world objects or require a cost-intensive maintenance infrastructure. MuseumID provides a free and easy solution to create and use museum object identifiers. There is no need to replace already established inventory numbers or to run a complex technological infrastructure. MuseumID is a proposal to the International Council of Museums (ICOM) for a recommendation about museum identifiers and museum object identifiers.