The book "Numerical Analysis and Its Applications" is a comprehensive collection of revised contributions from the 4th International Conference on Numerical Analysis and Its Applications, which took place in June 2008 in Lozenetz, Bulgaria. It includes 61 carefully selected full texts as well as 13 invited contributions that have undergone two rounds of review. The topics covered span a wide range of current aspects of numerical analysis and highlight recent advances in the fields of physics, chemistry, engineering, and economics. A particular focus is on numerical approximation, computer-aided geometry, numerical linear algebra, and the numerical solution of transcendental equations. Additionally, numerical methods for differential equations, numerical modeling, and high-performance computing are addressed.