nadia_f
  Junior Editor

Those are parentheses. They basically close off a section in math, and they use the PEMDAS (Order of Operations - Must use in order) protocol (or multiply two numbers) such as:
Ex:
3(2+3) + 8(2-1) =
(3 x 5) + (8 x 1) =
15 + 8 = 23
Parentheses (Answer what's in the parentheses first)
Exponents (Do the math for the exponents)
Multiplication (Multiply any numbers or variables)
Division (Divide any numbers or variables)
Addition (Add any numbers or variables)
Subtraction (Subtract any numbers or variables) more »

It means that they agree with what the person above was saying.

Lyrics, Flirting, Teasing

That is a star (for numbers and stuff)

It's a crying face.