common attachment file types are .pdf (adobe reader), .doc (Microsoft Word), .jpg (jpeg image), and .zip (compressed files of any file format).
PDF Format
PDF is the format commonly used for email attachments because it is universal. It can be opened by Adobe Software, which most people have on their computer.
Because PDF format is more or less 'universal' - Almost all word processors can read documents in PDF format.
PST is the file format which is created by Microsoft Outlook to save its entire database such as contacts, emails, attachments, notes, images etc.On the other hand, Outlook Express stores and saves their data into a DBX file format.To know more difference about MS-Outlook and Outlook Express, read the KB article about Microsoft support (From the given source):
programmable game notation file format used by most chess softwares for recording game.
The ASF file format system, also known as "Associated Streaming Format" is used to compose data stream in a file. They compose data streams in files like HTML or MPEG4.
The DVM file extension is associated with the DVM Movie File Format. It is used to store small animations and movies, developed by Magic Software.
Psw is a file format associated with programs. Microsoft uses the .psw file format. It can be used in mobile word processing.
Psw is a file format associated with programs. Microsoft uses the .psw file format. It can be used in mobile word processing.
Wpostx is the format used by Windows Live Writer. As such it is a text format which does not lend itself to conversion to a bitmap image format such as JPEG.
It is a kind of format file in a computer wherein it stores music playlists. It is the proprietary format file that is used in Windows Media Player with version 9 to 12.
The DGN CAD file format is used in large structure projects. Such as buildings, ships, highways. Professionals who work on buildings would use this format everyday.