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# Installation

[](){: #general }

## General Information

The two main interfaces for running tests with `Common Test` are an executable
program named [`ct_run`](ct_run_cmd.md) and the Erlang module `m:ct`. `ct_run`
is compiled for the underlying operating system (for example, Unix/Linux or
Windows) during the build of the Erlang/OTP system, and is installed
automatically with other executable programs in the top level `bin` directory of
Erlang/OTP. The `ct` interface functions can be called from the Erlang shell, or
from any Erlang function, on any supported platform.

The `Common Test` application is installed with the Erlang/OTP system. No extra
installation step is required to start using `Common Test` through the `ct_run`
executable program, and/or the interface functions in the `ct` module.