And that doesn't make sense!

So we say that ∞∞ is undefined.

Infinite Sets

Digging deeper into this subject reveals the idea of different sizes of infinity like ℵ₀ (aleph-null), ℵ₁ (aleph-one) and the Continuum.

Conclusion

Infinity is a simple idea: "endless". Most things we know have an end, but infinity doesn't.