Interactive Guide to Calculus Limits

Getting Infinitely Close

Discover the single most important idea in calculus—the **limit**—not through equations, but through interactive stories and visuals.

The Never-Ending Journey to the Wall

Imagine you're standing in a room. You decide to walk to the wall, but with one strange rule: with every step, you can only go **half the remaining distance**. This is a famous idea called Zeno's Paradox. Will you ever reach the wall? Try it yourself!

You are at the starting line. The wall is 100 units away.

You get closer and closer, but never technically touch it. Yet, we know your ultimate destination. The **limit** of your position is the wall. A limit isn't about *arriving*, it's about the value you're zeroing in on.

Why We Need This "Fuzzy" Idea

Derivatives: Speed Right Now

How can you have a speed at a single instant if no time passes? It's a puzzle! Calculus solves this by finding the average speed over a super tiny interval of time, then uses a limit to see what speed you're approaching as that interval shrinks to zero. This limit is the **derivative**.

Imagine a curve representing your journey, and the limit helps us find the slope (your speed) at a single point on that curve.

Integrals: Area of a Curve

Finding the area of a square is easy, but what about a shape with a curvy top? We "cheat" by filling it with tons of skinny rectangles we can measure. The more rectangles we use, the better the fit. The limit of the area of these rectangles as we approach an infinite number of them is the **integral**.

Imagine filling a curvy shape with countless tiny rectangles. The limit is the exact area.

Seeing Limits in Action: The Pothole

Consider a function that's a perfect line, except for a single "pothole" at x=2 where it's undefined. We can't stand *on* x=2, but we can ask what height the road is approaching. Hover over the chart to see.

Hover on the chart to explore

The Uncrossable Line

Some functions have lines they get closer and closer to but never cross, called **asymptotes**. Explore the function f(x) = 1/x to see what happens when x gets very large or very close to zero.