This book presents an introduction into Robinson's nonstandard analysis.

Nonstandard analysis is the application of model theory in analysis. However, the reader is not expected to have any background in model theory; instead, some background in analysis, topology, or functional analysis would be useful - although the book is as much self-contained as possible and can be understood after a basic calculus course. Unlike some other texts, it does not attempt to teach elementary calculus on the basis of nonstandard analysis, but it points to some applications in more advanced analysis. Such applications can hardly be obtained by standard methods such as a deeper investigation of Hahn-Banach limits or of finitely additive measures.