Wikipedia:Image Use Policy

Wikipedia:Image Use Policy

Descriptive file names are also useful. A map of Africa could be called "Africa.png", but quite likely more maps of Africa will be useful in Wikipedia, so it is good to be more specific in a meaningful way, e.g. "Africa political map Jan. 2012.png", or "Africa political map with red borders.png". Check whether there are already maps of Africa in Wikipedia. Then decide whether your map should replace one (in each article that uses it) or be additional. In the first case give it exactly the same name, otherwise a suitable other name. Avoid special characters in filenames or excessively long filenames, though, as that might make it difficult for some users to download the files onto their machines. Note that names are case sensitive, "Africa.PNG" is considered different from "Africa.png". For uniformity, lower case file name extensions are recommended.

You may use the same name in the case of a different image that replaces the old one, and also if you make an improved version of the same image – perhaps a scanned image that you scanned again with a better quality scanner, or you used a better way of reducing the original in scale – then upload it with the same title as the old one. This allows people to easily compare the two images, and avoids the need to delete images or change articles. However, this is not possible if the format is changed, since then at least the extension part of the name has to be changed.