Collocation is an important item in linguistics research. It is ad- dressed differenty in different types of research. Here we at- tempt to get a clearer idea of the concept of collocation from vari- ous angles of linguistics. Moreover, we would like to list some typical examples of collo- cations according to the areas of usage. As to the ways of teach- ing and learning of collocations, we tend to highlight the impor- tance of incidental learning as well as intentional learning.