: Indicates it is a year-end "Hot 100" or most-played list.
: Suggests a compressed archive meant for downloading the entire collection at once. Context on 2021's Top Music : Indicates it is a year-end "Hot 100" or most-played list
wikipedia.org/wiki/Billboard_Year-End_Hot_100_singles_of_2021">Billboard Year-End Hot 100 instead? : Indicates it is a year-end "Hot 100" or most-played list