1) What is an API?
application programming interface, interacts with a different software component or ressource.
2) In the article the author compares Java API to Twitter API. What is the main difference between these two APIs?
While the Java API is accessed via the Java Developer Kit the Twitter API is web based.
3) The section in the article about abstraction is important, try to understand it and write down an abstraction from your daily life.
One example is the starting of a PC. The Enduser usually only presses one button and then enters a password to acces the machine while many different processes need to happen in the background to start the PC aswell as all programs.