The definition of an institution is an established custom or practice, or a group of people that was formed for a specific reason or a building that houses the group of people. Marriage is an example of a cultural institution.
Contextual targeting is a type of targeting on the Google Display Network in which you select specific keywords or topics and then allow AdWords to identify websites that are a good fit for your keywords and targets.
Positioning, in a marketing context, is the process of identifying an appropriate market niche for a product, service or brand and getting it established it in that area. The endeavor is further broken down into those three categories.