Package

In Move, smart contracts are organized into Packages. A contract is the primary unit of deployment; once uploaded to the blockchain, it is assigned a unique, immutable address that others can use to call its functions.

A package acts as a container for modules (i.e. contracts), which serve as distinct namespaces for defining types (structs) and logic (functions).

package 0x...
    module a
        struct A1
        fun hello_world()
    module b
        struct B1
        fun hello_package()

Package Structure

Locally, a package is a directory with a Move.toml file and a sources directory. The Move.toml file - called the “package manifest” - contains metadata about the package, and the sources directory contains the source code for the modules. Package usually looks like this:

sources/
    my_module.move
    another_module.move
    ...
tests/
    ...
examples/
    using_my_module.move
Move.toml

Package Address

Each package is identified by a unique address. This address is only relevant for internal use, to distinguish and reference packages inside the project. This addresses do not represent on chain addresses. Some special packages have reserved addresses.