They provide a channel in which people can communicate directly to their congressmen/ back them to pass legislation on your behalf.
The six purposes of the Constitution found in the Preamble are: 1) form a more perfect union. 2) establish Justice. 3) insure domestic tranquility. 4) provide for common defense. 5) promote the general welfare. 6) secure the blessings of liberty to ourselves and our posterity.
A political movement that represented the common people against wealthy business interests.
Have a great day :)