# Step By Step Calculus » 9.0 - History and Applications

History and Applications
In the 17th century, when Calculus was developed, the idea of limit was implicit. Later on, Cauchy discussed limits in his Cours d’analyse (1821). However, it was not well presented. The German Mathematician Weierstrass first presented the rigorous method of limits publicly in the 1850s and 1860s.
Limit plays a central role in understanding important mathematical concepts like the Law of Large Numbers, the Law of the Iterated Logarithms and the Central Limit Theorem which have applications in measuring the consistency of estimators, in measuring the fluctuation of a process (e.g. stock market), in signal processing, in characterizing Internet traffic, in parameter estimation for system identification, and so on.