 Understanding the infinite was the major focus of Euler's research.While some of Euler's proofs may not have been acceptable under modern standards of rigor, his ideas were responsible for many great advances.First of all, Euler introduced the concept of a function, and introduced the use of the exponential function and logarithms in analytic proofs

Euler frequently used the logarithmic functions as a tool in analysis problems, and discovered new ways by which they could be used.