In the seventies, Philippe Delsarte in a seminal work developed a method in Algebraic Combinatorics that yields upper bounds for the cardinality of codes with given minimal distance as a solution of a linear program. This method, also called the Delsarte method, or polynomial method, was developed in the framework of Association Schemes , which is the most general framework dealing with finite metric spaces.This method also obtains bounds in more general situations, such as lower bounds for designs (combinatorial and spherical).