A human language. For example, English, French, and Chinese are natural languages. Computer languages, such as FORTRAN and C, are not. Probably the single most challenging problem in computer science is to develop computers that can understand natural languages. So far, the complete solution to this problem has proved elusive, although a great deal of progress has been made. Fourth-generation languages are the programming languages closest to natural languages.

Fourth-Generation Language
Often abbreviated 4GL, fourth-generation languages are programming languages closer to human languages than typical high-level programming languages. Most 4GLs are used to access databases. For example, a typical 4GL command is

FIND ALL RECORDS WHERE NAME IS "SMITH"

The other three generations of computer languages are

• first generation: machine language
• second generation: assembly language
• third generation: high-level programming languages, such as C, C++, and Java.