C++ is a programming language that is portable, maintainable, and supports input/output operations. It allows problems to be broken down into data, functions, and applying functions to data to solve problems. C++ code is organized into blocks delimited by curly braces. It uses comments prefixed by // or between /* and */. The main function defines the starting code. Output is produced using cout and <<. Namespaces provide context for identifiers, and the std namespace is used for standard functions and objects.