The book describes methods for constructing, researching and applying spline functions in numerical analysis. The most detailed are the approximation of the function, numerical differentiation and integration, the solution of boundary value problems for ordinary differential equations" The presentation is relatively simple and accessible to a wide range of readers familiar with the basics of numerical analysis. Kinga can serve as a teaching aid for students of universities and universities. A significant part of the results is published for the first time, and much attention is paid to the construction of algorithms that are effectively implemented on computers. From this point of view, the book is interesting for scientists and engineers who apply spline methods in practice.