Open and Save Files in Formats Supported by Word Source:
Microsoft Tips A file format defines the way that information is
stored in a file, so that a specific program can open and save
that file. A file's format is indicated by a three-letter or
four-letter extension after the file name. For example, when one
saves a new document in Microsoft Word, Word by default stores
the document in Word format with a .doc file extension. Word can
directly open and save documents in some file formats. For
documents in other formats, Word uses file format converters for
opening and saving. The most commonly used converters are
installed with Word by default - unless the user or the
administrator chooses to make them unavailable on the computer.