PL/I is a procedural

Procedural programming

Procedural programming can sometimes be used as a synonym for imperative programming , but can also refer to a programming paradigm, derived from structured programming, based upon the concept of the procedure call...

, imperative

Imperative programming

In computer science, imperative programming is a programming paradigm that describes computation in terms of statements that change a program state...

 computer

Computer programming

Computer programming is the process of designing, writing, testing, debugging, and maintaining the source code of computer programs. This source code is written in one or more programming languages. The purpose of programming is to create a program that performs specific operations or exhibits a...

 programming language

Programming language

A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....

 designed for scientific, engineering, business and systems programming applications. It has been used by various academic, commercial and industrial organizations since it was introduced in the 1960s, and is actively used .

PL/I's principal domains are data processing

Data processing

Computer data processing is any process that a computer program does to enter data and summarise, analyse or otherwise convert data into usable information. The process may be automated and run on a computer. It involves recording, analysing, sorting, summarising, calculating, disseminating and...

, numerical computation, and scientific computing; it supports recursion

Recursion

Recursion is the process of repeating items in a self-similar way. For instance, when the surfaces of two mirrors are exactly parallel with each other the nested images that occur are a form of infinite recursion. The term has a variety of meanings specific to a variety of disciplines ranging from...

, structured programming

Structured programming

Structured programming is a programming paradigm aimed on improving the clarity, quality, and development time of a computer program by making extensive use of subroutines, block structures and for and while loops - in contrast to using simple tests and jumps such as the goto statement which could...

, linked data structure

Linked data structure

In computer science, a linked data structure is a data structure which consists of a set of data records linked together and organized by references ....

 handling, fixed-point, floating-point, complex, character string

String (computer science)

In formal languages, which are used in mathematical logic and theoretical computer science, a string is a finite sequence of symbols that are chosen from a set or alphabet....

 handling, and bit string handling.