An array of data which represents a coherent and discrete set of time.

We note that the term is widely used in different contexts (videography, photography, data recording, data analysis). Often it is used colloquially with imprecise semantic meaning. Therefore, the definition here focuses on its use within electron microscopy and we do not claim the definition to be ubiquitously applicable.With \"coherent\" we refer to the data within a frame being in some way logically and looked at as one unit. Furthermore, we refer to discretization of time not in the sense of smallest possible discretization because data frames may be dependent on extended exposure time periods or might also represent results of processing averaged sub-frames e.g. during analyses.