Hello guys I am ROMEO 64 (sounds weird I guess but who cares. :D).. Alright....Ever wondered what happens when you login to your Facebook account?
WARNING - geeky stuff ahead! Quit now if sleepy :D
You cannot imagine how much of hidden stuff happens when you press your login button.
Your computer tries to connect to the DNS server which helps your computer identify the IP address corresponding to the Facebook domain. Even this process is complicated. If the domain name to IP address mapping isn't available in your DNS server cache, it tries to connect to several other DNS servers to know the mapping. This may involve as many as 8 message exchanges across various parts of the world and it truly happens in the blink of an eye! All of this is taught in the Computer Networks course, and trust me, it was an amazing course!
Your login details are confidential. They cannot be sent over the channel (wire/wireless) as a plain text. So, everything is encrypted using a secure cipher suite. This ensures not only privacy of your message (no one gets to know your password), but also integrity of the message (no one can alter the message packet). All of this is taught in Cryptography and Network Security course.
Your message packet containing your login details goes to one of the several severs of Facebook. The servers work in a coordinated fashion for load balancing. Remember, billions of people use Facebook and if all of them login at the same time, a single machine won't be able to handle the load and so, several servers are needed. Your data is secure with the servers. Additionally, your data is distributed across several servers. These concepts are taught in Operating Systems/Distributed Computing. Several cloud computing concepts are also involved here!
Then your login details are verified at the server end. How amazing it is that you are identified so quickly in the database of about a billion (1,000,000,000) users in the blink of an eye. Also note that Facebook doesn't have your password! It just stores a hash of your password. Storing passwords will be dangerous because a breach of security at the server might leak all the passwords and so, the passwords are hashed and then stored. All of these concepts are a part of databases course.
When your search for stuff on Google, a lot of Artificial Intelligence and Natural Language Processing is involved. Imagine how smart the computers are that they are able to distinguish between "I can do it" and "Gimme a soda can" - Artificial Intelligence it is!.......