The sign is a very informal way of expressing a number of positive emotions, ranging from general esteem to love for the recipient of the sign. A similar-looking but unrelated variation (thumb toward the palm rather than thumb extended) appears in heavy metal music culture as a "devil's horns" hand-sign.
Deaf Heritage dates the origin of the ILY to 1905. However, resident students of deaf schools from the early 20th century do not recall seeing the sign anywhere until the 1970s.
The sign received significant media exposure with Richard Dawson's use of the ILY in his signoff from each episode of the Family Feud, which he hosted from 1976 to 1985. Presidential candidate Jimmy Carter reportedly picked it up from a group of Deaf supporters in the Midwest and, in 1977, during his Inauguration Day parade, flashed the ILY to a group of Deaf people on the sidewalk.