A file extension identifies the type of data contained in the file, and enables the operating system to choose an appropriate application to open the file, without needing to examine the data....
When Saving As... type the name then .jpg and it will be saved as a jpg. However jpgs are pictures and if it dosent save as a jpg it might have some issues such as being too big of a file for a jpg,...
WAV is Window's native lossless audio format
.AIFF is Apple's native lossless audio format
.MP3 is a common compressed audio format
.OGG is slightly less common
There are many many more