Hello.,

Core concepts are defined as an big ideas i.e., before moving into secondary things you need to complete preliminary things.

For example to move into a bigger aspect's of study you need to complete your primary education. The concept is somewhat similar to evolution of humans. First you need to complete the selected course at a particular time designed to it and you will get credit's for your performance with which you can move further towards another destination.

Hope this helps you out. Good luck