An Instructor's profile is visible for everyone, a student's profile is visible to himself only.
In the future we're considering the idea of making students' profiles visible to other students and instructors if you choose, so you'll be able to show your accomplishments and works.
Anyway and any case - your login details, such as email, password and social networks you use for fast login ARE PRIVATE. For those who really want to know how is it possible that we even don't know your password.
Keep your computer clean, use good passwords and don't forget to logout if your computer isn't private - and no one else will get access to your accounts on Classerium or elsewhere.