+## Overview
+
+The Friendica translation process is based on `gettext` PO files.
+
+Basic worflow:
+1. `xgettext` is used to collect translation strings across the project in the authoritative PO file located in `view/lang/C/messages.po`.
+2. This file makes translations strings available at [the Transifex Friendica page](https://www.transifex.com/Friendica/friendica/dashboard/).
+3. The translation itself is done at Transifex by volunteers.
+4. The resulting PO files by languages are manually updated in `view/lang/<language>/messages.po`.
+5. PO files are converted to PHP arrays in `view/lang/<language>/strings.php` that are ultimately used by Friendica to display the translations.
+
+## Translate Friendica in your favorite language
+
+Thank you for your interest in improving Friendica's translation!
+Please register a free Transifex account and ask over at [the Transifex Friendica page](https://www.transifex.com/Friendica/friendica/dashboard/) to join the translation team for your favorite language.
+
+As a rule of thumb, we add support for a language in Friendica when at least 50% of the strings have been translated to avoid a scattered experience.
+For addons, we add support for a language when if we already support the language in Friendica.
+
+## Add new translation strings
+
+### Supported gettext version
+
+We currently support the gettext version 0.19.8.1 and actively check new translation strings with this version.
+
+If you don't use this version, it's possible that our checks fail (f.e. because of tiny differences at linebreaks).
+In case you do have a Docker environment, you can easily update the translations with the following command:
+```shell
+docker run --rm -v $PWD:/data -w /data friendicaci/transifex bin/run_xgettext.sh
+```
+
+### Core
+
+Once you have added new translation strings in your code changes, please run `bin/run_xgettext.sh` from the base Friendica directory and commit the updated `view/lang/C/messages.po` to your branch.
+
+### Addon
+
+If you have the `friendica-addons` repository in the `addon` directory of your Friendica cloned repository, just run `bin/run_xgettext.sh -a <addon_name>` from the base Friendica directory.
+
+Otherwise:
+
+ cd /path/to/friendica-addons/<addon_name>
+ /path/to/friendica/bin/run_xgettext.sh -s
+
+In either case, you need to commit the updated `<addon_name>/lang/C/messages.po` to your working branch.
+
+## Update translations from Transifex
+
+Please download the Transifex file "for use" in `view/lang/<language>/messages.po`.
+
+Then run `bin/console po2php view/lang/<language>/messages.po` to update the related `strings.php` file and commit both files to your working branch.
+
+### Using the Transifex client
+
+Transifex has a client program which allows you to sync files between your cloned Friendica repository and Transifex.
+Help for the client can be found at the [Transifex Help Center](https://docs.transifex.com/client/introduction).
+Here we will only cover basic usage.
+
+After installation of the client, you should have a `tx` command available on your system.
+To use it, first create a configuration file with your credentials.
+On Linux this file should be placed into your home directory `~/.transifexrc`.
+The content of the file should be something like the following:
+
+ [https://www.transifex.com]
+ username = user
+ token =
+ password = p@ssw0rd
+ hostname = https://www.transifex.com
+
+Since Friendica version 3.5.1 we ship configuration files for the Transifex client in the core repository and the addon repository in `.tx/config`.
+To update the PO files after you have translated strings of e.g. Esperanto on the Transifex website you can use `tx` to download the updated PO file in the right location.
+
+ $> tx pull -l eo
+
+Then run `bin/console po2php view/lang/<language>/messages.po` to update the related `strings.php` file and commit both files to your working branch.
+
+## Translation functions usage
+
+### Basic usage
+
+- `Friendica\DI::l10n()->t('Label')` => `Label`
+- `Friendica\DI::l10n()->t('Label %s', 'test')` => `Label test`
+
+### Plural
+
+- `Friendica\DI::l10n()->tt('Label', 'Labels', 1)` => `Label`
+- `Friendica\DI::l10n()->tt('Label', 'Labels', 3)` => `Labels`
+- `Friendica\DI::l10n()->tt('%d Label', '%d Labels', 1)` => `1 Label`
+- `Friendica\DI::l10n()->tt('%d Label', '%d Labels', 3)` => `3 Labels`
+- `Friendica\DI::l10n()->tt('%d Label', 'Labels %2%s %3%s', 1, 'test', 'test2')` => `Label test test2`
+- `Friendica\DI::l10n()->tt('%d Label', 'Labels %2%s %3%s', 3, 'test', 'test2')` => `Labels test test2`