i have a question ...

Microsoft Word 2007, why put "X" at the end of "doc" Extension? what didn't do "doc" Extension? and what did now "docx" Extension?

i just need to know WHY MS Word 2007 use "X" any Solid Reason? or how much Reasons??? please give your answer in One Short line. thanks in Advanced.

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    I noticed that too. There may be some "formal" reason listed below as an Answer. But I'm pretty sure it has to do with making people with 2007 software feeling left out. There is no reason to invent a new suffix unless you wanted to leave people out of the loop. A suffix says this: "Oh .doc, open Word."; "Oh .docx, Open at least Word16". Smart business means make the largest profit gains and exhaust the market. Release a new product when you've done this. Add support for old products for a limited time to keep opinions of your business positive. Goal: return customer; loyalty or brand loyalty. – ejbytes Nov 3 '16 at 2:24
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    @ejbytes No. Really, just no. I wish I could downvote comments. A new and totally incompatible file format is not a “formal” reason. It is the only reason. – Daniel B Nov 3 '16 at 17:44
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    @DanielB Why is doc and docx incompatible? On the same note, who invented .doc and consequentially created the new .docx? Were NOT talking about incompatibility between two OS's or even architecture like Unix/PC or PlayStation/XBox. There are plugins that will allow .docx files to be opened and read w/older v's of MS Word which is backwards compatibility (plugin allows '03 MS Word documents w/the new suffix. Backwards compatibility is a decision in this case, based on a business model. HTML didn't stop being used when javascripts were introduced or php or css not even with html5 or css3. – ejbytes Nov 9 '16 at 8:47


It was an (at the time) new XML-based format, and most word processors would not have been able to automatically detect and handle it if it were simply a .doc extension, so I'm assuming that's why they decided a distinct file extension was appropriate.


The main reason is that there was a huge format change from a proprietary encoding of the documents to an XML based format. They then renamed the extension with an "x" at the end to signify this. There is also the issue that the format is not backwards compatible with older Word products unless you download a patch, so this makes it that these products don't try an open the documents. It also gives an indication to other non Word products if they can read the file since it's XML based.

Here is a relevant article that goes a bit more into details :http://blog.online-convert.com/doc-vs-docx-file-extensions/

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