A wink is a facial expression made by briefly closing one eye. A wink is an informal mode of non-verbal communication usually signaling shared hidden knowledge or intent. However, it is ambiguous by itself and highly dependent upon additional context, without which a wink could become misinterpreted or even nonsensical. For example, in some regions of the world, a wink may be considered rude or offensive. And depending on the relationship of the people involved, a wink could possibly constitute a sexual gesture. Winking is one of the more subtle gestures, usually involving eye contact between those involved. In most cases it is only meant to be known by the sender and their intended receivers, but in some cases can be more widely intended.