How to check Files Format | File Extension | Find File Extension
A file format or file extension is the ending of a file that helps identify the type of file in operating systems, such as Windows. In Windows, the file format is a period that is often followed by three characters, but may also be one, two, or four characters long.
For example,
the file name "myfile.txt" has a file format of ".txt",
the file name "myfile.mp3" has a file extension of ".mp3",
the file name "myfile.avi" has a file extension of ".avi".
in other words file format is the last characters after the dot (.) in a file's name.
Example: .jpg .exe .zip .mp4 .ico .png .apk .rar .txt .docx .avi .mp3 .mov