The various definition on distributed system are given & none of them are satisfy &none of them are agreement with any of other. For our purpose it is sufficient to give loose characterization:
The definition have several aspect but it should consists autonomous components that is seems as single system. The one of the most important character of distributed system is difference between the various computer & the way they communicate are mostly hidden from user. Which helps to user easy to understand as real world.
Distributed system should also be relatively easy to expand or scale which is also called the principle of distributed system. This means that having the individual computer but the same time, but hiding how the computer actually take part in system as a whole.