title: Query-level feature
text: # Query-level feature
  
  A query-level feature or QLF is a ranking feature utilized in a machine-learned ranking algorithm.
  
  Example QLFs:
  
  * How many times has this query been run in the last month?
  * How many words are in the query?
  * What is the sum/average/min/max/median of the BM25F values for the query?
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