Literally is a very commonly misused word. It is the opposite of figuratively.
literal – exactly the truth without exaggeration, nothing added or left out
figurative – using figures of speech, metaphors, or symbols
What people often do is to use literally without thinking of what it means. Earlier this year, someone in Hong Kong wrote "Its literally raining cats and dogs." (The first word is wrong: It's means it is. "Its" means possessed by it.) Now I have not noticed the Hong Kong Observatory mentioning any animals falling out of the sky. That is what the word literally appears to mean. Was the writer making a mistake with the word literally?
The (idiomatic) phrase "raining cats and dogs" means a heavy rain. The phrase is figurative and means that there is so much rain that it is similar to cats and dogs falling from the sky. It is assumed that the reader understands that this phrase is a wild exaggeration. Some people say, "It's raining cats and dogs and I just stepped in a poodle." The word poodle sounds like puddle; that is supposed to be a joke....
Adding literally to the sentence logically suggests that animals are now falling out of the sky. What the writer is doing is exaggerating (hyperbole) to make his point that there is a lot of rain. Many people object to a non-literal use of the word literally. For hundreds of years writers have used the word literally in a figurative manner. And for a long time some people, such as English teachers, have objected.
Here are some examples:
1. He is literally having kittens.
2. After eating the hot curry, her mouth was literally on fire.
3. His eyes were literally glued to the TV set.
In the first sentence, "having kittens" means he is angry. I suppose a cat having kittens is in a bad mood. Writing "literally having kittens" means very angry. The word literally is just a creative substitute for very. In the second sentence, to describe someone's mouth as being "on fire" just means that it feels painful. Again the word literally is a replacement for very. In the last sentence "eyes glued to the TV set", means that he is watching TV and never looks away at anything else. Again the word literally emphasises that he is not paying attention to anything else. If I said His brain had figuratively turned into congee it would not sound as interesting as if I had said His brain had literally turned into congee.
The book Sorry, I'm British by Ben Crystal and Adam Russ defines literally as "A word used for emphasis, 98% of the time incorrectly". So the law of common usage means that literally no longer literally means literally .
This non-literal literally is logically problematic, but not always wrong. It is common and is used by many good writers. However it is often overused. I dislike the non-literal literally and it can be confusing for second language learners. I would suggest that students avoid using the non-literal literally. Use it in a story when you want to exaggerate something and use the literal literally in other types of writing.