This page contains details on the installation of OCaml on Mac and Windows.
Mac
The easiest way to install OCaml on Mac is to use a package manager, which is a separate piece of software that must be installed first. Once that is done, it keeps track of which other pieces of software are necessary to build a functioning system. These instructions suggest the use of Homebrew, but there are other options. If you prefer, you can read about them at the official OCaml install page.
To begin, you will need to open a Terminal where you can enter commands. Type the following command to install Homebrew:
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
Once that finishes, you can follow it with the commands to install OCaml:
brew install ocaml brew install opam
At this point, the basic OCaml compilers and tools we need should be installed.
Windows
The easiest way to install OCaml for Windows uses an installer program available here.
Since OCaml was designed to work in a Unix environment, the installer gives you a curated version of the Cygwin environment, complete with Unix-like command prompt. After the installer runs you should see an icon for OCaml64 (or possibly OCaml32) on your desktop. Open that and you will have a command prompt where you can navigate your file system, compile files, and run them.