The Declaration of Independence served three major purposes. The first included the reasons for separation. Among the reasons for separation were statements about the king, George III. It was said that he was a harsh and evil king and that the colonists shouldn't have to be under his rule. It also said that the citizens were patient, submissive, and long-suffering people. These statements were made to win public support for the Declaration.
The second major purpose included a plan for a new theory of government. In this section of the Declaration, Jefferson stated the basic principles of democracy. They were, "all men are created equal; they are endowed by their creator with certain unalienable rights; among these rights are: life, liberty, and the pursuit of happiness." The purpose of this new government was to secure these rights.
The third major purpose for the Declaration of Independence was to present a formal declaration of war. This basically stated that, war did exist. If the Patriots failed to win independence, the leaders of the revolution could be judged guilty of treason against the British Crown and executed.
The result of the Declaration of Independence was that the colonists had gained their freedom. They had freedom of religion and had a better government. Look at the world today and see what it has accomplished.