The rudiments of programming in science will be explained theoretically and using a practical approach with many examples and exercises, mainly in C++ and Python. The structure of a program to be compiled or interpreted will be presented. The variables, data structure, loops, control structure, functions, and classes will be explained in detail. The strength of knowledge of the basics of programming techniques is the possibility (i) to access open source resources, (ii) customize the tools to solve their issues, and (iii) not depend on commercial software, but the “cost” to pay is to write the code by yourself.