Typing your site content in an editor like Microsoft Word is a great idea!  Word offers features like spelling and grammar correction that are indespensible for good content-authoring. However, when it comes time to transfer the content into your site, copying directly from MS Word is going to cause some formatting headaches. 

The reason for this, is that copying from MS Word copies not only your text, but quite a bit of additional styling information.  See what happens when you copy and paste the text "Two Words" from MS Word?

How to avoid the gnarley formatting?

For Drupal 7 and 8 Sites:

Your site editor has a paste from Word feature enabled. With your copied content on the clipboard, press "ctrl" +"shift" + "v" to paste a clean copy of unformatted text into your editor.

For Drupal 6 Sites:

We recommend an intermediary.  Or, put another way -- copy and paste your text into Notepad. (You can find it here:  " Start >> Programs >> Accessories >> Notepad ").

Then, copy it from Notepad into your CMS.  

The result is much simpler, and will look better to your visitors.