D, also known as dlang, is a multi-paradigm system programming language created by Walter Bright at Digital Mars and released in 2001. Andrei Alexandrescu joined the design and development effort in 2007. Though it originated as a re-engineering of C++, D is now a very different language. As it has developed, it has drawn inspiration from other high-level programming languages. Notably, it has been influenced by Java, Python, Ruby, C#, and Eiffel.

The D language reference describes it as follows:

D is a general-purpose systems programming language with a C-like syntax that compiles to native code. It is statically typed and supports both automatic (garbage collected) and manual memory management. D programs are structured as modules that can be compiled separately and linked with external libraries to create native libraries or executables.

D is not source-compatible with C and C++ source code in general. However, any code that is legal in both C/C++ and D should behave in the same way.

Like C++, D has closures, anonymous functions, compile-time function execution, design by contract, ranges, built-in container iteration concepts, and type inference. D's declaration, statement and expression syntaxes also closely match those of C++.

Unlike C++, D also implements garbage collection, first class arrays (std::array in C++ are technically not first class), array slicing, nested functions and lazy evaluation. D uses Java-style single inheritance with interfaces and mixins rather than C++-style multiple inheritance.

D is a systems programming language. Like C++, and unlike application languages such as Java and C#, D supports low-level programming, including inline assembler. Inline assembler allows programmers to enter machine-specific assembly code within standard D code. System programmers use this method to access the low-level features of the processor that are needed to run programs that interface directly with the underlying hardware, such as operating systems and device drivers. Low-level programming is also used to write higher performance code than would be produced by a compiler.

D supports function overloading and operator overloading. Symbols (functions, variables, classes) can be declared in any order; forward declarations are not needed.