Filter bubble
Etymology
Coined by activist Eli Pariser in his 2011 book The Filter Bubble, which argued that personalization algorithms at Google and Facebook were quietly editing what users could see. "Filter" is the algorithmic sorting; "bubble" conveys an enclosed, invisible membrane you don’t notice you’re inside. The strength of the effect has since been debated by researchers, but the term stuck.
noun phrase · /FIL-ter BUB-ul/
The narrowed information world an algorithm builds around you by showing more of what it predicts you already like.
What it names
It captures how two people can search the same term or open the same app and see near-opposite realities, without ever choosing to.
Example
I only realized I was in a filter bubble when a friend’s feed surfaced stories mine had silently buried for months.
Related idea
A filter bubble is imposed on you by an algorithm optimizing for engagement; an echo chamber is something you help build by choosing sources and communities that agree with you.