A cost is the value of resources that are used to achieve an end. The cost of an action is most often expressed in terms of money but a cost can also be expressed in terms of materials used, information, capital, labour and a number of other ways. Price focuses specifically on how much money is spent to achieve an end.
There is an extensive list of costs that can be incurred. Some costs are concrete such as the price of a raw material for manufacturing or the price of gasoline at a gas station. Costs that are obvious are called explicit costs. Explicit costs are easy to quantify and account for (especially for firms).
Other costs are less obvious and harder to determine such as the social cost, the effect of low employee morale or environmental costs. The value of a less obvious cost or implicit cost is determined by making assumptions to assign a value. Costs based on assumptions are not always exact, or easy to predict. Due to the unpredictive nature of implicit costs, it is difficult to account for the whole cost.
The cost of an action is often balanced against the potential gains from the action, this is called the net cost. The determination of a net cost analysis should take into account all costs that could be incurred in order to make an accurate comparison with the potential benefits. Comparing the costs and potential benefits of an action is called a cost benefit analysis.
When making a decision, one must choose to not do something. The benefits of whatever wasn't done is called the opportunity cost.
Here is a list of some costs which are commonly incurred: