OPAM stands for OCaml PAckage Manager.
It aims to suit to a vast number of users and use cases,
and has unique features:

* Powerful handling of dependencies:
versions constraints, optional dependencies, conflicts, etc.
* Multiple repositories backends: HTTP, rsync, git
* Ease to create packages and repositories
* Ability to switch between different compiler versions

Typically, OPAM will probably make your life easier if you recognize
yourself in at least one of these profiles:

* You use multiple versions of the OCaml compiler, or you hack the
compiler yourself and needs to frequently switch between compiler
versions.
* You use or develop software that needs a specific and/or modified
version of the OCaml compiler to be installed.
* You use or develop software that depends on a specific version of an
OCaml library, or you just want to install a specific version of a
package, not just the latest one.
* You want to create your own packages yourself, put them on your own
repository, with minimal effort.