4GL

4GL, or fourth-generation programming languages, refers to a class of high-level programming languages designed to be closer to human concepts and to increase programmer productivity. Unlike third-generation languages (3GLs) such as C or Java, which require explicit step-by-step instructions, 4GLs emphasize specifying the desired outcome, often through non-procedural syntax and domain-specific abstractions. They are frequently used for database querying, data manipulation, report generation, form or screen design, and business-oriented applications, with the aim of rapid application development (RAD).

Most 4GLs are domain-specific or declarative, offering built-in data modeling, query, and reporting facilities, and often generating lower-level code automatically or compiling to intermediate forms. Their use cases include creating reports, extracting and transforming data, and rapidly deploying business applications with minimal manual coding.

Examples of 4GLs include SQL, which is the most enduring and widely used 4GL for relational databases; IBM Informix-4GL, a standalone 4GL that integrated with the Informix database; and ABAP, the SAP application programming language, which is often categorized as a 4GL or 4GL-like language.

Over time, the distinction between 4GLs and other language families has blurred as modern development environments incorporate declarative and RAD features into general-purpose languages. The term 4GL is still used in historical contexts to describe older products and philosophies that prioritized rapid development and domain-specific tooling over explicit procedural coding.