Glue: How Google Measures Interaction with Special Search Features
The NavBoost counterpart for carousels, 'People also ask' boxes, and news features — measuring whether users interact with special elements, not just blue links
What is Glue?
Glue is the counterpart to NavBoost for special Google elements like carousels, 'People also ask' boxes, or news features. While NavBoost measures clicks on traditional blue links, Glue measures whether users interact with these special elements — tapping a weather carousel, expanding a 'People also ask' accordion, or scrolling through a news box.
Together, NavBoost and Glue form a complete picture of user satisfaction. NavBoost captures the traditional search journey: query → click → stay/return. Glue captures the modern search journey: query → interact with feature → find answer without clicking → satisfied. As Google's SERP evolves from ten blue links to rich features, Glue's importance grows.
Glue is fed by NavBoost (System 1) — they share the same behavioral data foundation. The difference is in what they measure: NavBoost extracts click patterns from the organic results, while Glue extracts interaction patterns from the special features layered on top.
Glue in the ranking architecture
Glue is both an Authority signal (A: primary) and a Trust signal (T: primary). This dual primacy makes sense: when users interact with a special feature containing a publisher's content, it signals both authority (the publisher was selected for the feature) and trust (the interaction validates the content).
Glue feeds into Tangram (System 3), the assembly layer that builds the final search results page. Tangram takes ratings from NavBoost and Glue and decides which results to show, in what order, and with which special features. This makes Glue a key input to the SERP composition process — not just a ranking signal, but a signal about how to present results.
The E-E-A-T dimension mapping also includes Experience (E: indirect) and Expertise (Exp: indirect). These indirect signals come from the fact that users who interact with a feature are engaging with the content at a deeper level than those who simply click a link — this deeper engagement signals both experience and expertise.
Implications for SEO practitioners
For publishers featured in special SERP elements, Glue creates both an opportunity and a risk. The opportunity: interaction with your content in a carousel or PAA box signals satisfaction to Google, which can improve your rankings. The risk: if users consistently skip your content in a carousel, that signals dissatisfaction.
For structured data, the implication is clear: rich results (carousels, FAQ accordions, news boxes) are not just display formats — they are interaction surfaces that Glue measures. A well-structured weather carousel that users tap through generates positive Glue signals. A carousel that users scroll past generates nothing.
The connection to Tangram means that Glue data influences not just rankings, but SERP composition. If users consistently interact with weather carousels for a query, Tangram will show more weather carousels for that query type. This creates a feedback loop: good interaction → more features → more interaction.