This page is an essay; it contains the advice and/or opinions of one or more Commons contributors. It is not a Commons policy or guideline, and editors are not obliged to follow it. Please update the page as needed, or discuss it on the talk page.
The inclusion criteria on Wikimedia Commons are not very precisely defined. This owes, in part, to this basic tension:
Commons exists to host content that is "educational"
Almost anything can in theory be used in an educational context
In practice, those who patrol the files for deletion queue see a large number of files where there is no obvious educational use. It should be possible for a Commons community member to discern, from the information accompanying an image or media file, what general sort of educational use it could be put to.
The presence or absence of useful metadata (such as descriptive text, meaningful categories, etc.) is significant to a discussion of whether or not something should be kept for educational purposes.
Almost any image could be used, in theory, to illustrate color correction. But the justification that an image could be used in this way would not constitute a useful argument in a "files for deletion" discussion. (Reductio ad absurdum: all images must be kept)