What is Culture?
Well it's one of those pluripotent words, that's for sure. The original meaning of the term, still preserved in such terms as cultivate, was the tillage of land and tending of crops. Cicero may have suggested that the mind was as worthy of cultivation as our fields, and this led to interpretation of culture as higher learning. Much later, anthropologists and archeologists appropriated the term for description of differences in human societies. Archeologists, in particular, use it to refer to the characteristic assemblages of artifacts left by ancient societies, which is to say the sufficiently durable remains of their tools, art, and manufacture.
Anthropologists use the same term to refer as well to beliefs, practices, and other intellectual elements common to groups of people. In a more diluted form, sociologists can use it to speak of the culture of a nation, region, college or even a corporation.
Of course individuals always differ among themselves in beliefs, practices, etc on the one hand, and widely share others across the spectrum of nations. At some point, then, the use of the term becomes too vague to be meaningful. My own perspective is that meaningful cultures really only exist in relative isolation. For many purposes, every middle class person in the world today lives in essentially the same culture - they use the same cultural artifacts, have similar knowledge, and share many common objectives. The globalization of culture is even more extreme at the top of the economic heap: Russian, Indian, American, Arab and Chinese oligarchs drive the same cars, buy yachts and jets from the same builders, and send their kids to the same elite prep schools and universities in the US and Britain.
Of course that's hardly to claim that there aren't systematic differences among these people and even their children. But as some point the commonalities are much more determinative of behavior. Those who imagine a purified "national" or religious culture, and every country has them, are deluding themselves. Barring a massive breakdown of international communications, an increasing globalized world culture seems inevitable.