# Why semigroups are important? [closed]

There is known a lot about semigroups, mostly about their inner structure etc. But is there any use of semigroups in the general Maths -- like that of groups?

-
A similar (but to my mind much better) question is mathoverflow.net/questions/20604/… I don't think this question is well-posed. Why is the wikipedia answer insufficient? –  Daniel Moskovich Feb 16 '11 at 14:22
Without saying what you mean by "the general Maths" this question is, as Daniel says, not well-posed. –  Yemon Choi Feb 16 '11 at 20:31
The question has been re-asked at mathoverflow.net/questions/55885 –  Yemon Choi Feb 18 '11 at 19:55