QUESTION: What is PCL?
ANSWER: PCL stands for "Printer Control Language." PCL was invented by Hewlett-Packard Corporation, and it is a language that is used for describing the text and graphics in documents. In other words, it is a page-description language.
Because PCL was invented by Hewlett-Packard Corporation, it is also known as "HP-PCL."
Files that contain documents described in the PCL language are normally called "PCL files"; hence, PCL is known as a file format as well as a language.
See also What is a page-description language?