The "tti" is an old East Asian custom of marking the year of birth with one of the twelve zodiac animals: rat, ox, tiger, rabbit, dragon, snake, horse, goat, monkey, rooster, dog, and pig. To ask "what is your animal sign?" is really to ask "in which year were you born?"
Its roots reach deep into ancient East Asian calendrics. The twelve branches were originally not animals but twelve symbols marking time and direction. They pointed to the hours into which a day was divided and to the compass directions, and paired with the ten Heavenly Stems (the energy of heaven) to form the sexagenary cycle that completes one round every sixty years. They are also closely tied to the observation of Jupiter, which circles the sky roughly every twelve years. Assigning a friendly, easy-to-remember animal to each of these symbols—spreading widely from around the Han dynasty—became the "tti" we know today.
A charming tale lies behind the animals' order. When the Jade Emperor declared he would grant rank in the order the animals arrived on New Year's morning, the rat secretly rode on the back of the diligent ox and, just before the finish line, leapt off to take first place, leaving the ox second. The same tale explains why the cat is missing from the twelve: the rat is said to have told it the wrong date on purpose, so the cat overslept—and this is why cat and rat have been on bad terms ever since.
This custom spread across East Asia—Korea, China, Japan, Vietnam—taking on each region's own color. Intriguingly, in Vietnam the cat replaces the rabbit and the water buffalo replaces the ox. People gauged a person's innate temperament by their sign, read mutual compatibility through principles such as the three harmonies, six unions, and clashes, and—when it was awkward to ask someone's age directly—asked their animal sign to work it out indirectly. They also symbolized a whole year by its animal, divining the mood and energy of the new year as "the year of such-and-such an animal."
As for its present, because the West has no equivalent, the tti today draws attention as fresh global cultural content. Each new year, products and designs themed on that year's animal pour out around the world, and animal-sign fortunes and compatibility enjoy steady popularity as multilingual content. This tender imagining of oneself as an animal remains vividly alive as a warm culture that, beyond dry analysis, connects person to person through story.