This chapter contains the most advanced topics we addressed so far in this book. We began with a discussion of multiuser systems and how to set up new user accounts. From there, we talked about ways you can share files from your Mac and connect to other computers that are sharing their files. Finally, you learned about some of the dangers of sharing your computer ”or even connecting it to the Internet. We talked about shutting off file sharing and turning on the built-in firewall to help keep your computer from being accessed by uninvited users.