# [Erlang/OTP](https://www.erlang.org)

**Erlang** is a programming language and runtime system for building massively scalable soft real-time systems with requirements on high availability. 

**OTP** is a set of Erlang libraries, which consists of the Erlang runtime system, a number of ready-to-use components mainly written in Erlang, and a set of design principles for Erlang programs. [Learn more about Erlang and OTP](http://erlang.org/doc/system_architecture_intro/sys_arch_intro.html).

[Learn how to program in Erlang](http://learnyousomeerlang.com/).

## Examples

There are several examples [on the website](http://erlang.org/faq/getting_started.html) to help you get started. The below example defines a function `world/0` that prints "Hello, world" in the Erlang shell:

```erlang
-module(hello).
-export([world/0]).

world() -> io:format("Hello, world\n").
```

Save the file as `hello.erl` and run `erl` to enter the Erlang shell to compile the module.

```sh
Erlang/OTP 24 [erts-12.2] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [jit]

Eshell V12.2  (abort with ^G)
1> c(hello).
{ok,hello}
2> hello:world().
Hello, world
ok
```

Learn more about the Erlang syntax of [modules](http://erlang.org/doc/reference_manual/modules.html), [functions](http://erlang.org/doc/reference_manual/functions.html) and [expressions](http://erlang.org/doc/reference_manual/expressions.html) on [Erlang.org](https://www.erlang.org).

## Installation

### Binary Distributions

Erlang/OTP is available as pre-built binary packages by most OS package managers.

```sh
apt-get install erlang
```

### Compiling from source

To compile Erlang from source, run the following commands. The complete building and installation instructions [can be found here](HOWTO/INSTALL.md).

```sh
git clone https://github.com/erlang/otp.git
cd otp
```

Checkout the branch or tag of your choice

```sh
git checkout maint-25    # current latest stable version
```

Configure, build and install

```sh
./configure
make
make install
```

Alternatively, you can use [Kerl](https://github.com/kerl/kerl), a script that lets you easily build Erlang with a few commands.

## Bug Reports

Please visit our [GitHub Issues](https://github.com/erlang/otp/issues) page for reporting bugs. The instructions for submitting bugs reports [can be found here](https://github.com/erlang/otp/wiki/Bug-reports).

### Security Disclosure

We take security bugs in Erlang/OTP seriously. Please disclose the issues regarding security by sending an email to **erlang-security [at] erlang [dot] org** and not by creating a public issue.

## Contributing

We are grateful to the community for contributing bug fixes and improvements. Read below to learn how you can take part in improving Erlang/OTP. We appreciate your help!

### Contribution Guide

Read our [contribution guide](CONTRIBUTING.md) to learn about our development process, how to propose fixes and improvements, and how to test your changes to Erlang/OTP before submitting a pull request.

### Help Wanted

We have a list of [Help Wanted](https://github.com/erlang/otp/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22) bugs that we would appreciate external help from the community. This is a great place to get involved.

## Awesome-Erlang

You can find more projects, tools and articles related to Erlang/OTP on the [awesome-erlang list](https://github.com/drobakowski/awesome-erlang). Add your project there.

## License

Erlang/OTP is released under the [Apache License 2.0](http://www.apache.org/licenses/LICENSE-2.0).

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