TITLE: What does the long curly line mean?
QUESTION [6 upvotes]: Sorry to sound incredibly ignorant, but I am...at least in math anyway. What does this symbol: $\int$ mean?

REPLY [6 votes]: It is the symbol for the Integral; it is a stylized 'S' because the concept of the integral is a related to the Sum, which starts with S. (the mathematical symbol for Sum is a capital sigma, ∑ -- which is S in the traditional Grek alphabet from which mathematics borrows so many symbols.)