Language > Widgets > About Runtime Distributions

# About Runtime Distributions

If your IDL application is intended to be run in an installation with an IDL development license, you do not need to create an IDL distribution. Simply package up your application files (either `.pro` files or `.sav` files, and any necessary data files) and distribute it to your users along with instructions describing how to install and launch the application.

If, however, you intend to distribute your application to users who do not have an existing IDL installation, or if you want your application to run directly from removable media such as a CD-ROM or DVD-ROM, you must create a runtime distribution. A runtime distribution contains the IDL executable files, dynamically-loaded library files, and resource files needed to execute an IDL application that has been packaged in an application `.sav` file.

In versions of IDL prior to version 7.0, there were two methods available to create a runtime distribution:

- using the Export feature of the IDL Development Environment’s Project interface (Windows and UNIX)
- using the `make_rt` script (UNIX only)

In IDL 7.0, these methods were replaced by the MAKE_RT procedure. MAKE_RT provides a cross-platform mechanism for building runtime distributions for multiple platforms.