They form a client-server model - which may, or may not, be a "distributed system" If the web apps and mobile apps are all communicating with a more-or-less mo

They form a client-server model - which may, or may not, be a "distributed system" If the web apps and mobile apps are all communicating with a more-or-less monolithic backend, it's not "distrbiuted", it's only client-server If the backend is distributed (and not just a DR failover), and/or compute is happening in the mobile or web apps as well, then you have a "distributed system" See also: - https://en.wikipedia.org/wiki/Distributed_computing https://en.wikipedia.org/wiki/Distributed_computing - https://en.wikipedia.org/wiki/Client%E2%80%93server_model https://en.wikipedia.org/wiki/Client%E2%80%93server_model