User Interface Evolution of YouTube (2005-2026): A Longitudinal Analysis from HCI Perspective

YouTube has evolved from a simple video-sharing website into a global social-media platform used by billions of viewers across diverse languages, abilities, and levels of digital experience. This study examines how its user interface changed from 2005 to July 2026 and what those changes imply for usability and user control. A longitudinal archival dataset of 22 YouTube homepage snapshots was collected from the Wayback Machine. Semiotic analysis traced changes in navigation, thumbnails, feedback mechanisms, account identity, and search, while a usability evaluation rated seven archive-visible dimensions on a 0-5 ordinal scale at representative checkpoints. Supporting structural properties of the archived HTML were also examined to identify implementation-level changes. The results identify five broad time periods: YouTube moved from explicit, text-heavy navigation and community ratings toward visual discovery, persistent identity, personalization, recommendation-driven feeds, and AI-assisted interaction. The descriptive HCI score increased from 2.86 in 2005 to 4.43 in July 2026, mainly through stronger consistency, efficiency, feedback, and accessibility support; user control improved more modestly as content discovery became increasingly algorithmically mediated. The findings suggest that successful interface evolution depends not only on adding functionality but also on preserving understandable signifiers, predictable interaction, and meaningful user agency.