A collection of commonly used VHDL constructs that can be shared by more than one design unit, that is, by multiple Entity Declarations, Architecture Declarations, Configuration Declarations, and Package Declarations. Packages consist of a Package Declaration and an optional Package Body. To use a package, you use a Use Clause in the VHDL Design File (.vhd).
Packages are stored in design libraries. For example, the Quartus® Prime Standard Edition software provides the lpm_components package in the lpm library. The Use Clause for a package associates the package to a library. Also, because the Quartus® Prime Standard Edition software automatically specifies the current project directory as the work library, the Compiler considers any packages it creates from a project's VHDL Design Files to be in the work library.
See "Section 2.5: Package Declarations" in the IEEE Std 1076-1993 IEEE Standard VHDL Language Reference Manual for more information on packages.