Sarcasm and irony
Often referred to as the 'lowest form of wit', sarcasm is often confused with irony. Sarcasm involves a composer (most commonly a speaker) saying something that is the opposite of what they really mean. The important difference between the two is that sarcasm is correctly defined as being a humorous and deliberately mocking or insulting the object or person towards whom it is directed. Sarcasm is most commonly used in spoken texts.
There are a number of forms of irony. In its simplest definition, irony occurs when what is said (verbal) is in contradiction to what is meant. Again, this should not be confused with sarcasm. Irony does not need to be as mocking or insulting as sarcasm.