If you email a Word document as an attachment, the recipient can open it in MS Word and save it as a Word document. If you are using web-based email such as G-mail, Yahoo Mail, MSN mail or Squirrelmail, go here.
If you are using Outlook, Outlook Express, Thunderbird, Eudora, or another local email client, you can attach the document directly from the MS Word window. Open the document you would like to attach. Left-click File, then Send To, then Mail Recipient (as Attachment)...
Your email client should open a new message window with the file attached. (If it does not open, try this alternative method.) You can add a message and recipient address, modify the subject if you like. Then Send it.
Many other applications provide tools for sending files as attachments. Look in the File menu for a Send... or Send to... selection.