A file extension is usually a set of three to four alphanumeric characters, preceded by a period, that are appended to the end of a filename to help you and your operating system determine what kind of data is stored in the file (E.g. .txt is a text file and .jpg is an image file).
Once the type of data has been determined, your operating system will select the relevant software to read the file. Sometimes however, you may find that your operating system chooses the wrong software or worse still - your operating system does not recognise the file type.
That's where dotwhat.net can help! We try to provide as much help as possible for every file extension, detailing any software that is required.