Air quotes are a form of body language and gesturing, usually paired with an accompanying word or phrase that is meant to imply a different meaning to the words or phrase being used. A similar form in print are called scare quotes, where a word is placed in quotation marks to cast doubt on the way the word should be interpreted. An example of the scare quote could be something like the following: Well the candidate “says” he won’t raise taxes.. This casts doubt on the meaning of the word, says, and in fact may convey the belief that the person writing the line does not believe the candidate is being truthful. Another way to use this would be to place the word, says, in italics.
If you were speaking this line, you might apply air quotes as an extra form of emphasis. The gesture usually means bringing the hands slightly above shoulder height, and near the face; though some have the hands slightly above and on either side of the shoulders. With each hand facing forward, and with the thumb, ring and pinkie fingers folded into the palm, the index and middle finger are held upward until the appropriate word or phrase are indicated as placed in quotation marks by bending the index and middle finger toward the palm.
Most people place their hands down after finishing a set of air quotes, since to leave them in potential air quote position would seem a little odd. Sometimes the gesture does seem somewhat redundant because people also have vocal tone which can help allow them to convey something like sarcasm, disbelief, satirical use of a word, or the suggestion that the word being used is euphemistic. Occasionally, people will also use air quotes when they are relating the speech of other people, which may include impression of the person in addition to whatever the person said.
There are a number of different synonyms for air quotes, and though the gesture is fairly well understood in English, other culture have different means of conveying air quotes. First, they may be called ersatz quotes (pronounce ersatz as airsotts), and they may also be called airsotts, reflecting the pronunciation. Ersatz is an interesting word choice, and translates to replacement, substitute or spare. It can also mean imitation, or artificial. The word itself may make sense in the context of air quotes since the gesture almost always indicates that the words or phrase being used are a replacement for other more accurate words that might be used instead.
Ersatz is German in origin, and Germany does have a different version of the air quote than do people in the US. Their version looks more like the German question mark, with one hand up and the other inverted. Many people who use air quote forms will try to replicate something that looks like quotation marks in their own language. This may or may not be similar to English quotation marks.