“…As any handbook will tell (Jannach, 2010 ; Ricci et al, 2016 ) RecSyss are meant to offer relevant information in myriad settings, basically dealing with situations where an abundance of information makes it hard to detect and select what is required in a specific situation, or with situations where information itself cannot be accessed. Recommender systems are now part of search engines (the PageRank algorithm), streaming providers (music, movies, podcasts), social networks (rankings in timelines, news feeds), webshops (suggesting similar products or services), platforms that mediate the gig economy (recommending short stays or car rides), and will no doubt feed into cyberphysical infrastructures [internet of things (Felfernig, 2019 ), smart cities (Quijano-Sánchez et al, 2020 ), connected cars, smart energy grids (Chadoulos et al, 2020 )]. On top of that behavioral advertising, which runs the business model of “free” services such as search engines and social networks, is a dedicated type of recommender system (Yun et al, 2020 ).…”