The Declaration of Independence starts with a title, asserting it as the unanimous assertion of all 13 colonies, declaring their independence as the United States of America. This is the way it is titled:
In Congress, July 4, 1776, a declaration by the representatives of the United States of America, in General Congress assembled.
Then, the opening paragraph of the Declaration says the following:
When in the Course of human events it becomes necessary for one people to dissolve the political bands which have connected them with another and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation.
The second paragraph of the Declaration begins with probably the most famous set of lines in what Thomas Jefferson wrote in the Declaration:
We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. — That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, — That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness.
After that, the Declaration goes on at some length with what Jefferson called "facts to be submitted to a candid world" -- points that demonstrated that the British king had been seeking to establish "an absolute Tyranny over these States" (the colonial states which were declaring their independence).
