It is clear that the final values of the variables in the example program depend on the order that statements are executed in. In general, given the same input data, a sequential program will always execute the same sequence of instructions and it will always produce the same results. Sequential program execution is deterministic.
The sequential paradigm has the following two characteristics:
the textual order of statements specifies their order of execution;
successive statements must be executed without any overlap
(in time) with one another.
Neither of these properties applies to concurrent programs.