DOC and DOCX formats are file extensions developed by Microsoft and that are used in MS Office Word.
However, the latter relates to more recent versions of the product and has almost superseded the DOC. The aim of its creation was to make it more ubiquitous and competitive.
Yet, the basic functionality remained: users can still perform habitual text formatting, make corrections, add pictures and photos, draw graphical objects, and create hyperlinks.
And sharing the document is now more convenient since the DOCX has become more compatible with other systems, which in turn, removes limits for its distribution.
This format first appeared in 2007 and was settled in the further versions of Word, such as 2010 and 2013 for Windows, and 2008 and 2010 for Mac OS X.
Its key difference from DOC is that this newer type of file extension has a smaller size than the previous one, which adds a significant benefit. Letter X means Xls - the markup language on which the updated version was created. The major part of the text processing software that cannot read the older extension, can convert it into the newer one.
Thus this document format can be easily opened in programs for both Windows and Mac OS.