Redis Sets are powerful data types that support powerful operations like intersections and unions. They are not in any order and are usually used when you want to perform an audit and see relationships between various variables. 

Redis Sets Use Cases

1. Analyzing Ecommerce Sales: Many online stores use Redis Sets to analyze customer behavior, such as searches or purchases for a specific product category or subcategory. For example, an online bookstore owner can find out how many customers purchased medical books in Psychology.
2. IP Address Tracking: Redis Sets are a great tool for developers who want to analyze all of the IP addresses that visited a specific website page or blog post, and to be able to ignore all of the duplicates for unique visitors with their SADD function.
3. Inappropriate Content Filtering: For any app that collects user input, it’s a good idea to implement content filtering or inappropriate words, and you can do this with Redis Sets by adding words you’d like to filter to a SET key and the SADD command.

Source: http://highscalability.com/blog/2019/9/3/top-redis-use-cases-by-core-data-structure-types.html