Sarcasm is writing the opposite of what you mean. It doesn't work in short form text (similar to Poe's Law) but people do it anyway because it works in their in

Sarcasm is writing the opposite of what you mean. It doesn't work in short form text (similar to Poe's Law) but people do it anyway because it works in their internal monologue that has vocal intonation. Even when it works, it's an obnoxious outburst and intellectually devoid of value. Snark is general obnoxiousness that adds no intellectual value.