We have a tendency to be sloppy about language in everyday usage, so that words like “cost”, “value” and “price” are used more or less interchangeably. But economists will tell you that the words have distinct meanings, and picking them apart is crucial to understand economic transaction. Suppose I am a carpenter and I make chairs: The cost of the chair is what it costs me to make it: raw materials, overheads, my own time, etc.