In the diagram attached, Account is the name of the class. Owner and Balance are attributes of that class. AddFunds and RemoveFunds are methods of the class.
Proxy servers can act to anonymize web requests by hiding their true source IP addresses and removing identifying information.
Steganography is the art of using cryptographic techniques to embed secret messages within other content.
Password complexity is driven by length, and a longer password will be more effective against brute-force attacks than a shorter password.