# Data Flow & Dynamic Variable Presets Usage

Dynamic contextual variables (see dedicated [glossary](https://app.gitbook.com/o/iFKI1JaxSfPoiGt4tT2k/s/6Yw9IRJ6KbbucQPwZUCZ/~/changes/394/recommendations-and-merchandising/concepts/strategies/rules/presets-default-algorithms/algorithms-appendix)) drive these presets recommendation rules:

* **`page_type`** determines which rule is triggered (homepage vs PDP vs cart).
* **`viewed_items`**, **`bought_items`**, **`cart_items`** feed “associated” and “similar” rules.
* **`recency`**, **`frequency`**, and **`monetary`** score freshness and priority.
* **`categoryId`**, **`productId`**, and **`user_recent_basket`** define the contextual scope for “products from variable”.

Flow overview:\
`User Event (Tag)` → `Contextual Variables updated` → `Rule Evaluation (Algo)` → `Filtered Product List` → `Display on Site / Feed Analytics`.