According to the reading, the integral $\int_{a}^{b} f(x) d x=$ ___ and the final result is a ___

Step 1 ：The definite integral of a function f(x) from a to b is the signed area between the x-axis and the function from x=a to x=b. It is computed using the Fundamental Theorem of Calculus, which states that if F is an antiderivative of f on [a, b], then \(\int_{a}^{b} f(x) d x= F(b) - F(a)\).

Step 2 ：The result of a definite integral is a number, not a function. This is because it represents the signed area under the curve, which is a scalar quantity.

Step 3 ：Final Answer: \(\boxed{\int_{a}^{b} f(x) d x= F(b) - F(a)}\) and the final result is a number.