Change

  If someone meant to say Ps and pronounce it Bees. would this confuse you :). Ps is for the P that is the start of Properties and Practice Each application should have some properties and follow certain practices. Properties: Scalable, Scale = Increase workload (horizontally scaling) Statless, no state should be shared among different application instances,  Concurrency, concurrent processing = Threads. Loosely coupled, decompose the system into modules, each has minimal dependencies on each other "modularization", encapsulating code that changes together "High cohesion".  API first, Interfaces, implementation can be changed without affecting other application. favor distribution of work across different teams.  Backing Services, "DB, SMTP, FTP ..." , treating them as attached resources, meaning they can easily be changed. Manageable, changing the internal state and O/P via external I/P,  Also regarding updating the application up while keeping the overal