A more thorough explanation:

Sedition is when someone uses language to encourage rebellion against the government. This can include speaking or writing words that promote disloyalty to the government, trying to change the government through illegal means, or inciting someone to commit a crime that would disrupt the peace.

In the United States, seditious conspiracy is a federal crime under 18 U.S.C. § 2384. This law makes it illegal for two or more people to conspire to overthrow the government, wage war against the government, or use force to prevent the execution of any U.S. law. If convicted, a person can be fined or imprisoned for up to 20 years.

Sedition has a long history in Anglo-American common law tradition. In the Elizabethan era, sedition was defined as inciting disaffection towards the state or authority. Colonies in North America also had their own sedition laws. For example, in the colony of New York, John Peter Zenger was prosecuted in 1735 under a seditious libel law for publishing written criticism of a public official. However, the jury refused to convict him because the content he published was true.

In 1798, the Alien and Sedition Acts were passed by a Federalist administration led by John Adams to prevent the ideas of the French Revolution from infiltrating the new Republic. The acts made it illegal to oppose any measure of the U.S. government or impede the operation of any U.S. law. The Democratic-Republican administration led by Thomas Jefferson repealed the acts in 1800.

Today, sedition is still a crime in the U.S., but the First Amendment's free speech protections limit the extent to which the government can criminalize it. In the 1969 Supreme Court case Brandenburg v. Ohio, a test was created requiring that speech must directly or imminently likely produce violence. Most modern seditious conspiracy convictions involve terrorist plots, such as in U.S. v. Rahman, where Muslim clerics were convicted under § 2384 for plotting to bomb buildings and assassinate political figures.