•  Abstraction 

1. Abstraction is "To represent the essential feature without representing the background details."
2. Abstraction lets you focus on what the object does instead of how it does it.
   
3. Abstraction provides you a generalized view of your classes or objects by providing relevant information
   
4. Abstraction is the process of hiding the working style of an object, and showing the information of an object in an understandable manner.

• Encapsulation 
1. Hiding the internal state and functionality of an objec...

Token-based authentication is a protocol which allows users to verify their identity, and in return receive a unique access token. During the life of the token, users then access the website or app that the token has been issued for, rather than having to re-enter credentials each time they go back to the same webpage, app, or any resource protected with that same token.

Auth tokens work like a stamped ticket. The user retains access as long as the token remains valid. Once the user logs out o...