What is culture?

Having encountered the "they all drink coke and wear blue jeans, so belong to the same culture", this page full of definitions of what culture is, is refreshing.

e.g.,

For the purposes of the Intercultural Studies Project, culture is defined as the shared patterns of behaviors and interactions, cognitive constructs, and affective understanding that are learned through a process of socialization. These shared patterns identify the members of a culture group while also distinguishing those of another group.

or

"Culture is the shared knowledge and schemes created by a set of people for perceiving, interpreting, expressing, and responding to the social realities around them"