Since this is supposed to be a brief introduction we will focus on the three most fundamental principles here.
There are not enough resources for everyone’s wants. Most resources are limited and there is only a certain quantity available for distribution. However people essentially have unlimited wants for those resources and hence try to get as much of them as possible (In other words: more is always better).
Because of the scarcity mentioned above, people are forced to make choices, since they cannot get everything they desire. This may be obvious when it comes to money (i.e. “Should I spend those 2$ on ice cream or on an apple?”), but holds true for all decisions we face in our life. For Example: On a sunny day you could either spend the day at the beach, or have a nice barbecue with your friends. If you chose the barbecue you obviously can’t go to the beach at the same time.
This term describes the value of what has been given up in order to get something else. Again this does not necessarily have to be a monetary value. In our example above, the opportunity cost of having a barbecue would be not being able to be at the beach at that time. In other words, opportunity costs are the possible benefits you could have received by taking an alternative decision.