Culture shock exactly means the impact you may feel when you enter a culture very different from one to which you are accustomed.
Culture shock is common among immigrants and foreign students. No matter how well you are prepared, there are many things in a culture that you cannot find in books. This is not simply about meeting new and unexpected things, but also failing to meet what you would never have believed would be missing from any culture. Differences in nonverbal communication and unwritten rules play a large part.
Culture shock is a state of impaired ability to function due to 3 things -
The absence of familiar or comforting characteristics of one's own culture (Converse... this may be countered by absence of distasteful elements of one's home culture, although by definition this is unlikely)
The presence of seemingly irrational, inscrutable, offensive, or even hostile aspects of the target culture. (Converse... at first, culture shock is staved off by novelty and idealization of the target culture, and in some cases this artificial bubble of perception may be perpetuated indefinitely).
Lack of ability, linguistic or otherwise, to gain cultural understanding rapidly enough to adapt to these changes. (Converse... inability to understand may prevent you from becoming offended)
Whenever we experience we should reminded ourselves that ((many)) people with Autism feel ((suffer) this way constantly.
If one has been living in another country for a long time - noted the obvious differences, felt comfortable, then begun to realize there are other more fundamental, but subtle differences - finally they will learn that folks have different ways of solving the same challenges. The problem is then that one may suffer even more severe cultural shock upon returning home. In some places the cars are too large, the people too hurried, families are not extended anymore. In others, comfort is all consuming - and, for others economic growth trumps concern for the environment or sometimes even for the people. And then, when someone asks, "how was it in..." and you begin to answer, the questioner (if not another expatriate or wanderer) begins to glaze over - and, is soon talking to someone else.
The presence of the above criteria will generally bring on culture shock. One criterion alone may be sufficient if it is of enough significance to the individual.
There may be a special category of culture shock called culture fatigue (see below) in which one is able to adapt via all the criteria above, yet over an extended period of time suffers fatigue from the cumulative effect of having to negotiate large numbers of seemingly trivial differences over a period of time.
Culture shock can also be caused by a heightened level of social awareness referred to as "societal acuity deviation".