YouTubei

Could you clarify what YouTubei refers to? Is it:

- the YouTube iOS app (often informally shortened),

- an internal project or code name used by YouTube,

- an open-source/reimplementation project named YouTubei,

- or a fictional/educational concept?

Also, would you like a factual article based on real-world information, or a hypothetical/fictional entry? If you provide the context, I’ll write a concise, neutral wiki-style article under 300 words.