The First Amendment allows citizens to express and to be exposed to a wide range of opinions and views. It was intended to ensure a free exchange of ideas even if the ideas are unpopular. Freedom of speech encompasses not only the spoken and written word, but also all kinds of expression (including non-verbal communications, like sit-ins, art, photographs, films, and advertisements).
The amendment protects not only the speaker, but also the person who receives the information. The right to read, hear, see and obtain different points of view is a First Amendment right as well.
The right to free speech is not absolute. The Supreme Court has ruled that the government may sometimes be allowed to limit speech. For example, the government may limit or ban libel (the communication of false statements about a person that many injure his or her reputation), obscenity, fighting words, and words that present a clear and present danger of causing violence.
The government also may regulate speech by limiting the time, place or manner in which it is made. For example, the government may require activists to obtain a permit before holding a large protest rally on a public street. – The United States Constitution, What It Says, What It Means, A Hip Pocket Guide