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in time, all software are meant to be executed sequentially. By sequential
execution we mean that the coded instruction will be executed one after another
implying only one portion of program being activated at any given time. Say, a
software has multiple modules, then only one of all the modules can be found
active at any time of execution.
In
software design, concurrency is implemented by splitting the software into
multiple independent units of execution, like modules and executing them in
parallel. In other words, concurrency provides capability to the software to
execute more than one part of code in parallel to each other.
It
is necessary for the programmers and designers to recognize those modules,
which can be made parallel execution.
The
spell check feature in word processor is a module of software, which runs along side the word processor itself.