Rename Your Media Files with… …Rename Media Files
It’s a bit odd that WordPress doesn’t let you rename your media files. For a feature with some usability questions and a lot of SEO questions (Google, of course, reads the filenames of images as a clue to what they’re about), it’s surprising that WordPress’s best out-of-the-box solution is to simply delete and reupload whatever files you’d like to have renamed.
Fortunately, most extensions to WordPress are a Google search away. This plugin lets you change both media files’ “titles” within WordPress (such as “Picture of the Sky”) and their URLs (…/picture-of-the-sky.jpg). Take note that you do have to change both separately.
Overall, a good plugin that solves what I think is an important problem, and the first I tried that doesn’t gate its most important features behind a Pro upgrade. If you’ve got some media file names to change, have a look!