Files with the PBL extension are libraries used by the PowerBASIC software development tools. The PowerBASIC brand of commercial compilers uses a dialect of the BASIC programming language.

PowerBASIC libraries feature a well defined interface used to invoke the collection of behavior implementations. PBL files are also used to implement most system services.

There are two versions of PowerBASIC compilers, one for DOS and one for Windows. The Windows version is of two types: a Console one and a Windows one. Both these types feature an extended BASIC syntax that includes Windows functions and support for calls to the Windows Application Programming Interface.