The sine function is a periodic function meaning that it repeats itself every so many (in the case of sine 2pi radians or 360^o). It has a range of -1 to 1 and has a domain for -∞ to ∞. Starting at the origin it increase to 1 at 90^o or pi/2 radians and then decrease to -1 at 270⁰ or 3pi/2 radians and then returns to 0 and 360^o or 2pi radians.

On the graph below the angle, in radians, is along the x axis and the value of the sine function for that angle is on the y axis.

Graph of y=sin(x)