A physically unclonable function, or PUF, is some physical structure with properties that are easy to verify, hard to predict, and practically impossible to clone. Ideally, this means it's a device-unique unchanging identifier, which can be used for improving security. However, it can be at odds with privacy and anonymity. This talk will give you an overview of the thirty years of history behind PUFs, and will include the most recent advances in research. The functions, structure, and design will be discussed, as well as devices and materials that have properties to base PUFs on.