Thank you for the opportunity to help you with your question!
Facebook Co Ltd puts first consumers' privacy. Think of a situation where someones facebook can be accessed by anyone, it sounds weired ! As a company , they have put the following steps in place to ensure consumer privacy:
1. Restriction of number of authorised devices to use for login. This ensures that consumers account cannot be accessed on a foreign device without his or her knowledge.
2. Password strenght recommendation. The password need to be of a given length and combinations to avoid cases by intruders
3. Each information about the user is restricted to only people he or she allows e.g friends, family etc.
4. Messaging services are contantly monitored with an ability to detect and block offensive messages as spam.
Please let me know if you need any clarification. I'm always happy to answer your questions.