Enable multilingual readers to more easily access and read content in multiple languages.
As a multilingual reader, when using the Wikipedia app, I want to...
- ...allow all languages I read to be set up in the app, so that I can access feed content in all the different languages in which I read Wikipedia.
- ...be able to quickly search across languages, so that I can easily find articles in all Wikipedia languages I read.
- ...be shown all relevant search results for articles in all languages I understand, so that I can quickly access the content (saving time spent on searching and navigating through articles).
Rationale (Why are we doing this)
- Better supports a significant minority of multilingual users. Data obtained from the iOS app (which already enables user selection of multiple languages) shows that around ~10% of users switching between the language in their searches daily.
- Improves access to more content for New readers. Many Indian New readers read content in English as well as in their native Indic languages.  This would allowing such users to access content across the various languages more easily.
- Builds a foundation to enable content translation contributions on Mobile. There are plans for example to extend the Content Translation feature to mobile. 
The following may be broken up into further sub-tasks.
- Feature/UI development:
- T190838: Add multiple language selection to app Settings
- T190839: Enable searching Wikipedia in multiple app languages
- T190922: Add language detection and selection to app onboarding
- T191302: Show add languages prompt for existing multilingual users
- T191075: [V2 Multilingual Enhancement] Show more relevant cross-language wiki results to multilingual users - may be de-prioritised as a V2 enhancement
- T190920: Enable customization of the feed in multiple languages
- Measurement and Testing:
- Documentation & Marketing
- T191640: Create an announcement card promoting the new multilingual feature on the Explore feed
- Update Android FAQs page
- Highlight/Promote the multilingual release in specific regions/countries/languages (?)
 Design brief (extended version of task description): https://docs.google.com/presentation/d/1q1kiRLBtwh8KZvRkP5WXqADJPVYBCZO_VK4S2cC7Tq8/edit#slide=id.p