C++ is a middle-level programming language developed by Bjarne Stroustrup starting in 1979 at Bell Labs. It runs on various platforms like Windows, Mac OS, and UNIX. The document provides an overview of key C++ concepts like basic syntax, comments, data types, variables, constants, operators, loops, functions, arrays, strings, pointers, references, structures, classes, inheritance, and input/output. It also lists common functions and their uses.