Nonstandard Analysis is a branch of mathematics that extends the traditional framework of calculus and analysis by introducing the concept of infinitesimals—quantities that are infinitely small and not zero. This approach allows mathematicians to rigorously work with these infinitesimal values, providing a new perspective on limits, continuity, and derivatives. Developed in the 1960s by mathematician Abraham Robinson, Nonstandard Analysis offers tools for understanding mathematical concepts in a more intuitive way. It has applications in various fields, including mathematical logic, model theory, and even physics, where it can simplify complex problems involving continuous change.