Hotwire/Turbo primitive that delivers targeted HTML fragment updates (append/prepend/replace/update/remove/before/after) to specific DOM ids. Comes in two flavors: HTTP Turbo Streams (response-driven, effectively a rebranded/modernized successor to js.erb templates — usable outside Rails) and WebSocket Turbo Streams (Rails-specific broadcasts over Action Cable). In Yaroslav Shmarov's talk used for reset-filter buttons, filter counts, one-time API token reveals, and infinite pagination (a Turbo Frame rendered inside a Turbo Stream).