What is a file extension and how do you change it?

What is a file extension and how do you change it?|||A file extension is the ending part of a file that tells you what type of file the file is... For eg: you could have yoursong.MP3 now the .MP3 part tells you that the file is a mp3 file... to change that you could do this but it might not work.. Right click on it and go properties, then at the top it will have a bar that tells you the file name just change the .mp3 to .wav or something like that.. To convert files like mp3 to wav you should use a program like switch that will convert it for you.. Other types of files may need other programs to convert.. Hope this helps!!|||There are couple free file extension libraries online, one of which is http://www.liutilities.com/products/winb鈥?/a> You can practically find all explanations for any type of file extension.