Smell-o-vision

Smell-o-vision is the name given to a type of interactive television where the viewer can 'smell' what is happening on the programme. Viewers are given a card or booklet (usually distributed in television listing magazines and newspapers such as the TV Guide) which have a several numbered squares. It utilises 'scratch 'n' sniff' technology, and at certain points during the TV programme, a number appears on screen which relates to a certain square on the scratch 'n' sniff card.

It is rarely used, because of the limits of scratch 'n' sniff technology, and because of problems with distributing the Smell-o-vision cards. It was used as a gimmick for the Children in Need charity event.