It was written on the 2nd of July, 1776, and made public two days later, on the 4th of July. This document is very important, because it represents the freedom of the American Nation.
Its purpose is to explain to the whole wide world what mistakes made the British Parliament regarding the colonists' rights and life, and what facts led them to a war for secession with Britain. The document serves very well, effectively, its purpose, because it makes its points clear.
The ideas put forth in this document are very well expressed, and Thomas Jefferson wrote truthful things, except for a few facts. On one hand Thomas Jefferson accused the king of Britain's wrongdoings, but mostly the Parliament was the one to blame. On the other hand he accused the king for the slavery business, though that was not truth, nor fair.
Thomas Jefferson wrote the Declaration of Independence so that everybody would understand its purpose, but the tone is very adequate to the high-class people.