This is an example of exchange theory. In sociology, exchange theory has to do with maximizing benefits while also minimizing costs. When applied to Bill and Cathy's situation, they are taking advantage of each other's skills in order to minimize costs - Bill can cook and Cathy can't (so they can prepare food on their own) and Cathy can repair stuff and Bill can't (so they don't have to get a handyman).
Localization is a service which is used to adapt a product or page to a specific market. A localization strategy addresses customer behaviors, purchasing habits, and general cultural differences in each country it operates.
Changes in factors like average income and preferences can cause an entire demand curve to shift right or left. This causes a higher or lower quantity to be demanded at a given price.
Observation is a constant source of knowledge for man about himself, others and the world around him. The observational method is one of the most used in the social sciences and has some curious aspects.
