Deciding which file formats to use in a repository is a crucial task in the long-term preservation of digital objects. Due to constant changes in technology, one can only give recommendations that can very well be outdated quickly. However, there are criteria for file formats that support long-term-preservation. Various types of objects, such as video, audio, images or texts need different considerations to determine the appropriate file format. Even if a format meets all prerequisites for long-term preservation, it is important to be aware of new developments and to adapt existing file formats if necessary. In order to preserve digital objects over a long period of time, it is important to consider in which form they should be stored. Not all file formats prove to be reliable in this respect. On the one hand, this text is intended to provide important knowledge for the evaluation of formats. On the other hand, it provides an overview of the currently frequently recommended formats so that even formats not mentioned or new formats can be evaluated for their suitability for long-term archiving.