MIME types let a user’s web browser know what a given file is so that it knows how to handle that file (display it, download it, pass it to a browser plug‑in, and so on). Many common MIME types are already defined and can’t be directly changed. If you have a new type of file and people are having trouble accessing it (for example, instead of downloading the file, the user’s web browser tries to display the file as a text document), you may have to add a MIME type for that sort of file.

You will need to know what the MIME type should be and what extensions (the last 3 or 4 characters of a filename preceded by a period) the file name typically has (jpg and jpeg are both common extensions that appear on the end of JPEG picture files). Separate all extensions with a space and do not include a period.