They give more/additional information about a certain topic of research.
They help learns to know what they may expect to see on the field
A: A command economy<span> is one in which a centralized government controls the means of production. ... There are </span>advantages<span> and disadvantages of </span>command economy<span> structures. </span>Command economy advantages<span> include low levels of inequality and unemployment and the common good replacing profit as the primary incentive of production.</span>
Can you please include more information place region relative location physical system and human system
