i18n stands for internationalization, where 18 characters between the i and n are omitted in favour of the 18.

As you want your project to be as accessible as possible, providing multiple interface languages is a necessity. This makes two things (very!) important: Firstly: using a standard format to store translation keys, so it is easy to translate with established tools. Secondly: Promote translatability and further ease translating. This can be done on one of the translation services listed here. You can use hosted ones, which are free for FOSS projects, or self-host an instance of a translation-website.

Pootle

translate.sourceforge.net/wiki/pootle

pootle.locamotion.org - the official server instance

Allows self-hosting. Extends the python web-framework/CMS Django.

Get Localization

www.getlocalization.com

Free for open projects, commercial service provider offering paid subscription for private repos and more options.

Transifex

www.transifex.net

Free for open source projects. Otherwise, limited to one project and 15k words on the free plan. Monthly subscription fee for more.

CloudIn

crowdin.net

Free for open source projects.

Weblate

https://github.com/nijel/weblate

Self-hosting, Django-based.