Several social networking websites try to protect the personal information of their subscribers, as well as provide a warning through a privacy and terms agreement. On Facebook, for example, privacy settings are available to all registered users: they can block certain individuals from seeing their profile, they can choose their "friends", and they can limit who has access to their pictures and videos. Privacy settings are also available on other social networking websites such as Google Plus and Twitter. The user can apply such settings when providing personal information on the Internet. The Electronic Frontier Foundation has created a set of guides so that users may more easily use these privacy settings and Zebra Crossing: an easy-to-use digital safety checklist is a volunteer-maintained online resource.