A preamble is like a big introduction before something important - like before you make a speech. The Preamble to the United Nations Charter is the big introduction to the United Nations, which is an organization made up of lots of countries around the world. In the Preamble, the countries all talk about why they joined the United Nations and the goals that they have. The Preamble explains why the United Nations exists and what the countries hope to do together. It says that the countries all want to work together to save future generations from the horrors of war and to help everyone have rights and freedoms.