# Overview of Single-Variable Calculus

In this lesson, we'll give a broad overview and description of single-variable calculus. Single-variable calculus is a big tool kit for finding the slope or area underneath any arbitrary function $$f(x)$$ which is smooth and continuous. If the slope of $$f(x)$$ is constant, then we don't need calculus to find the slope or area; but when the slope of $$f(x)$$ is a variable, then we must use a tool called a derivative to find the slope and another tool called an integral to find the area.