Final answer:
Hate speech, categorized as 'fighting words' or threats, is generally unprotected by the First Amendment due to its potential to incite violence or illegal actions. Other unprotected speech includes obscenity, libel, slander, and expressions that threaten national security.
Step-by-step explanation:
The type of speech that is generally considered unprotected by the First Amendment is hate speech. This sort of expression can fall into the category of 'fighting words' or threats, which are not protected. Moreover, while political speech and religious speech are highly protected under the First Amendment, there are important restrictions on free speech, like obscenity, libel and slander, incitement to lawless conduct, and speech that violates national security among others. These restrictions are in place to prevent harm or illegal activities that can be incited by certain expressions.
For example, the right to express racist views through words is protected, but using symbolic speech such as cross burnings, which can constitute a threat or intimidation, is not always protected. Ultimately, certain types of harmful expression, like hate speech, have been limited to protect individuals and the public order without completely stifling the freedom of expression.