Sarcasm is a form of verbal irony where the speaker says something that is the opposite of what they actually mean. This is often done to be humorous or to express a negative opinion in a more subtle way.
For example:
* "Oh, great, another sunny day in the desert. Just what I needed." (The speaker is actually complaining about the hot weather.)
* "You're doing a great job at cleaning your room, I can see it." (The speaker is being sarcastic because the room is messy.)