C++ began as “C with Classes,” a project Bjarne Stroustrup started in 1979 at Bell Labs. In his own answers to frequently asked questions, Stroustrup writes that he started work on what became C++ in 1979 and that “the name ‘C++’ was used late” in 1983. The name signifies an evolutionary step from C: in C, the ”++” operator can be read as “next,” “successor,” or “increment.”
Stroustrup records that “the first commercial implementation was released October 1985.” The early language was distributed using a translator called Cfront, which turned C++ source into C that could then be compiled by an ordinary C compiler. This let C++ run anywhere C already ran.
The central idea C++ added to C was the class: a way to bundle data together with the functions that operate on it, supporting the object-oriented style that Stroustrup had admired in the Simula language. C++ kept C’s efficiency and low-level control while adding these higher-level abstraction tools.
Stroustrup explains that the language is not called “D” because it is an extension of C rather than a replacement that removes features. That design choice, keeping compatibility with C, helped C++ spread quickly through the large community of existing C programmers and made it one of the most widely used languages in the world.