Image source: youtube When you execute something synchronously, you wait for it to finish before moving on to another task. When you execute something asynchronously, you can move on to another task before it finishes. In Synchronous program execution, your program is executed line by line, one line at a time. Each time a function is called, program execution waits until that function returns before continuing to the next line of code. In solving many engineering problems, the software is designed to split up the overall problem into multiple individual tasks and then execute them asynchronously. For example, In computing, sorting a list is an example. The quicksort routine, for example, splits the list into two lists and sorts each of them by calling itself recursively. Real life example: SYNCHRONOUS You are in a queue to get a movie ticket. You cannot get one until everybody in front of you gets one, and the same applies to the people queued behind you. ASYNCHRONOUS