This document provides an overview of key concepts from Class XI computer science, including data types, variables, constants, operators, control structures, and functions in C++. It discusses fundamental data types like int, char, float, and double, as well as type modifiers. Variable declaration and initialization are explained. Control structures covered include if-else statements, switch statements, for, while, do-while loops, and the break and continue statements. The document also defines functions and distinguishes between built-in and user-defined functions.