Google Docs also supports Microsoft Word's. Since everything is saved in Google's cloud, you don't need to worry about losing your work-Docs autosaves after every single keystroke, so in the event of a crash you should be able to pick up right where you left off, down to the letter. If you want the basic features of Microsoft Word, you don't need to look any further than Google Docs-it does all your basic word processing needs, and it is tightly integrated with Google Drive and other products.
Google Docs, which is easily the most popular Microsoft Word alternative on this list, is free to everyone with a Google account.