"The dollar is now worth more than the dollar, which will be obtained in the future, eg one year, as it can be invested and this will bring additional revenue."

This principle is the most important position in the whole theory of finance and investment analysis. Based on this approach to assessing the economic efficiency of investment projects.

- Determine the level of effectiveness of the independent investment project for its acceptance or rejection;

- Determine the level of performance mutually exclusive projects (relative efficiency) to evaluate the possibility of adopting one of several alternatives.