File formats. Microsoft has a nasty habit of periodically changing the default format of the documents you write then save. They did it again with their 2007 version and carried it on with the 2010 version. The newer versions will put an ending on files “.docx”. The previous versions of Word used “.doc”.
Word is a very useful and durable program and for almost everyone, it makes no sense to go out and buy the newest version every 3 years or so. So at this point, lots of people are still using 2002 or 2003 versions. Some even the 2000 version even though Microsoft no longer supports that product or the 2002 (XP) Office product.
If you bought or buy the 2007 version or the 2010 version, Word will have no problem opening documents that were saved by previous versions. However, when you give or send a Word document you created in the newer version to someone else who has NOT installed one of those newer versions, they will not be able to open it. Microsoft has a solution for those of you who have not yet upgraded. Go their web site and search for “2007 converter pack.” There you will find a free download. Once installed (you only have to do this once), your system will seamlessly open .docx files without a problem.
If however you send a lot of Word documents to a lot of people, you may want to consider changing the default format for Word in your computer to the older 97-2003 format .doc.