Constitution Annotated from the U.S. Congress
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
This website offers analysis of what the First Amendment means and the history of how it came into being enshrined in the U.S. Constitution.