There are many ways to categorize human culture, from national cultures, which can be seen in the differences between Americans and Canadians; to religious cultures, such as the differences between Orthodox Jews and Roman Catholics; and ethnic cultures, such as the differences between African-Americans and Indian-Americans. Other types of culture, including subcultures and cultures based on factors such as gender and sexuality, also exist.
There are many different ways to classify and define what is and is not a culture. Cultures can be nationalistic or regional, and the differences between different national or regional cultures become apparent when two people from different parts of the world interact. Certain things that are considered impolite in Western cultures are considered normal in many Eastern cultures, such as a disregard for personal space. Different ethnic or religious cultures can exist within a single nation or region as well, and different subcultures can exist within those ethnic or religious cultures.
In terms of human society, the word culture refers to learned behaviors, practices and points of view that are characteristic of a specific group of people. Generalizations about culture can lead to stereotypes, such as the idea that all Americans are fat, lazy, rich people who eat junk food and watch lots of TV. However, some overarching observations can be made about specific cultures without resorting to derogatory stereotypes, and these observations have been the subject of study for generations of social scientists.
Humans aren't the only animals that experience culture. Scholars have identified cultural traits that exist among groups of animals as well. Chimpanzees have dominance hierarchies in their social groups, which is one way of defining a culture.