The notation "f(2)" represents the value of a function f when the input is 2. In mathematics, a function is a rule that assigns each input exactly one output. For example, if f is defined as f(x) = x + 3, then f(2) would equal 5, since 2 + 3 equals 5. To find f(2), you simply substitute the number 2 into the function's equation. This process is essential in various fields, including algebra and calculus, as it helps in understanding how functions behave with different inputs. Each function can have different rules, leading to different outputs for the same input.