You’ve heard the stories about iCloud accounts getting hacked; the ones that make the news are celebrities’ accounts, but there may be people wanting to get into yours too. In addition to your Apple ID–the email address you use to identify your account–your password is the key that lets you into that account.
But anyone can pretend to be you, and attempt to get into your account, saying they’ve forgotten the password, and then attempting to answer the security questions that you chose when setting up the Apple ID. If they get through them, because they know the name of your first pet, your favorite sports team, and whatever else, they can access your account. Unless you add an additional layer of security.
Read the article on the Intego Mac Security blog.