Supply and DemandThe
 market system is driven by supply and demand. Take beer again. Let's 
say people want more beer, meaning the demand for beer is high. This 
demand means you can charge more for beer, so you can make more money on
 average by changing wheat into beer than grounding that same wheat into
 flour. More people start making beer and, after a few production 
cycles, there is so much beer on the market that prices plummet. 
Meanwhile, the price of flour has been increasing as the supply shrinks,
 so more producers buy up wheat for the purpose of making flour - and 
on, and on.
This extreme and simplified example does encapsulate 
the wonderful balancing act that is supply and demand. The market is 
generally much more responsive in real life, and true
 supply shocks are
 rare – at least ones caused by the market are rare. On a basic level, 
supply and demand helps explain why last year's hit product is half the 
price the following year.
 Costs and BenefitThe concept of costs and benefits encompass a large area of economics that has to do with
 rational expectations and
 rational choices. In any situation, people are likely to make the 
choice that has the most benefit to them, with the least cost, or, put 
another way, the choice that provides more in benefits than it costs. 
Going back to beer, the breweries of the world will hire more employees 
to make more beer, only if the price of beer and the sales volume 
justifies the additional costs to the payroll and the materials needed 
to brew more. Similarly, the consumer will buy the best beer he or she 
can
 afford, not, perhaps, the best tasting beer in the store.
 This
 extends far beyond financial transactions. University students perform 
cost benefit analysis on a daily basis, by focusing on certain courses 
that they believe will be more important for them, while cutting the 
time spent studying or even attending courses that they see as less 
necessary.
 Of course,
 everyone knows someone who has seemingly made a poor life choice. 
Although people are generally rational, there are many, many factors 
that can throw our internal accountant out the window. Advertising is 
one that everyone is familiar with. Commercials tweak emotional centers 
of our brain and do other clever tricks to fool us into overestimating 
the benefits of a given item. Some of these same techniques are used 
quite adeptly by the lottery, showing a couple sailing a yacht and 
enjoying a carefree life. This image and its emotional message ("this 
could be you") overwhelm the rational part of your brain that can run 
the very, very long odds of actually winning. Cost and benefits may not 
rule your mind all the time, but they are in charge more than you think -
 especially when it comes to the next concept. (This free thinker 
promoted free trade at a time when governments controlled most 
commercial interests. Check out
 Adam Smith: The Father Of Economics.)
 
Everything Is in the IncentivesIncentives
 are part of costs and benefits and rational expectations, but they are 
so important that they are worth further examination. Incentives make 
the world go round, and sometimes go wrong. If you are a parent, a boss,
 a teacher or anyone with the responsibility of oversight, and things 
are going horribly awry, the chances are very good that your incentives 
are out of alignment with what you want to achieve.
 We'll
 take a safe example, however, of – you guessed it – a brewery. This 
particular brewery has two sizes of bottle: one 500ml bottle and a 1L 
bottle for couples. The owner wants to increase production, so he offers
 a bonus to the shift that produces the most bottles of beer in a day. 
Within a couple days, he sees production numbers shoot up from 10,000 
bottles a day to 15,000. However, he is soon deluged with calls from 
suppliers wondering when the shipments of the 1L bottles are going to 
come. The problem, of course, is that his incentive focused on the wrong
 thing – the number of the bottles rather than the volume of beer – and 
made it "beneficial" for the competing shifts to cheat by only using the
 smaller bottles.
 When
 incentives are aligned with organizational goals, however, the benefits
 can be exceptional. Some incentives have been proven so effective that 
they are common practice at many firms, such as
 profit sharing,
 performance bonuses and employee shareholding. However, even these 
incentives can turn disastrous if the criteria for the incentives falls 
out of alignment with the original goal. Poorly structured performance 
bonuses, for example, have driven many a
 CEO to
 take temporary measures to juice the financial results enough to get 
the bonus – measures that often turn out to be detrimental in the longer
 term.
 Putting It All TogetherScarcity
 is the overarching theme of all economics. It sounds negative, and it 
is one of the reasons economics is referred to as the
 dismal science,
 but it simply means that choices have to be made. These choices are 
decided by the costs and benefits that impact the choice, leading to a 
dynamic market system where choices are played out through supply and 
demand. On a personal level, scarcity means that we have to make choices
 based on the incentives we are given and the cost and benefits of 
different courses of action. This is a very broad look at what is, 
believe it or not, a very compelling subject. These concepts feed into 
others, like
 comparative advantage,
 entrepreneurial spirit, marginal benefit and so on. The world is wide 
with choices, so the field of economics is wide with theories, laws and 
concepts that explore those choices.
  
ConclusionThese
 concepts aren't powerful laws that force human interactions into preset
 patterns. Rather, they are a recognition of the patterns that emerge 
from hundreds, thousands, millions and billions of individuals making 
choices with the information they are given. While knowing these 
concepts may not allow you to fundamentally change the world, it will 
help explain a lot. (Discover the theories that shaped the way we've 
come to understand economics. Refer to
 The History Of Economic Thought.)