Microsoft Word offers an online word processor that can be found at https://office.live.com/start/Word.aspx. There are some other online word processors too, including Writer and Google Drive.
In order to use Microsoft Word Online, writers must sign in with their Microsoft account. Without signing in, they can't get access to the blank document. This is an easy way to share documents and work on them together with others. In order to do this, the document must be shared with the other people who want to work on the document.
Word Online offers the same features as Word offline includes, such as templates. It also has a similar layout so there isn't too much of a learning curve for people coming from Word offline. Documents are shared with other people by going to File and then Share, and then typing in their email address or giving them a link to the document.