Series

Series[f, {x, x0, n}] generates a power series expansion for f about the point x=x0 to order n.

Examples

Taylor series of Sin:

Series[Sin[x], {x, 0, 5}]
(* x - x^3/6 + x^5/120 + O[x]^6 *)

Series of Exp:

Series[Exp[x], {x, 0, 4}]
(* 1 + x + x^2/2 + x^3/6 + x^4/24 + O[x]^5 *)

Please visit the official Wolfram Language Reference for more details.