https://www.youtube.com/watch?v=oV9rvDllKEg

Tony Horein - Communicating sequential processees

1. concurrency is about modelling and parallelism is about execution
2. concurrency is a sub-set of parallelism
3. processes share memory - mutability
4. processes don't share memory but communicate using message passing
   1. copying the data from one process to another

related

1. semaphore
2. message passing