From Lostpedia

Jack has several tattoos on his body, which are most notable on his left arm and shoulder, and his back.

Left forearm

Jack's left forearm tattoo

Jack's tattoos are first seen in the pilot, when he removes his shirt to assess the extent of his injuries. They are discussed by Kate and him in "House of the Rising Sun" before they leave on their trek to the Caves.

In "The Man from Tallahassee", while Jack is waiting outside of Ben's house, some kind of drawing is visible on his left arm. This is another tattoo that he received before arriving on the Island, its origins are yet to be explained.

Jack's forearm tattoo is also seen in "Outlaws" when he is giving Kate a gun from the marshal's case, in "One of Us" when Jack is handing towels to Juliet on the beach, and clearly in "Catch-22" when Jack is helping Juliet build her tent. It can also be seen in "The Shape of Things to Come" when Jack is taking pills from the medical suitcase, and less clearly when Doctor Ray's body is pulled from the water.

Back

Jack also has a small tattoo on the upper left part of his back. It can be seen very briefly in "Pilot, Part 1" after he says "standard black". It is very noticeable in the early scenes of "Something Nice Back Home".

Left shoulder

Jack's tattoo on his left shoulder are of the number 5, and 4 Chinese characters just underneath. In "Stranger in a Strange Land", we learn that this was tattooed on Jack in Phuket, Thailand, by a Thai woman named Achara. She claims to have the gift of sight to see someone's inner identity. She is able to "see who people are", and "mark them". According to Achara, Jack is "a leader, a great man" but this makes him lonely and angry. He forces her to give him the tattoo, despite her protests that she will get in trouble if she does. Her brother and a gang of Thai locals later attack Jack, and he is forced to leave the country when this is discovered.

Literal translation

Achara's contribution to Jack's tattoo --("Stranger in a Strange Land")

Pattern of Jack's left shoulder tattoo

In "Stranger in a Strange Land" while Jack is in captivity on Hydra Island, Isabel remarks on the irony of the tattoo, and asks Jack if he knows what they mean. She later translates the characters' meaning to "He walks amongst us, but he is not one of us." When Jack is told this, he says "That's what they say. That's not what they mean." The translation of the Chinese characters given by Isabel is however, not literally accurate.

A word by word explanation of the 4 Chinese characters on the tattoo:

1. 鷹 means eagle.
2. 击 means strike, as a verb.
3. 長 means long.
4. 空 means "sky", "space", void, "empty".

These characters are pronounced ying ji chang kong (in PinYin). These four characters are taken from a famous poem written by Chairman Mao Tse-tung (Mao Zedong). It may be roughly translated as "Eagles high, cleaving sky", or more simply, "the Eagles fly up on the sky". But the poem itself has a deeper meaning. In the end of the first stanza, the poet asks, "who masters fate's rise and descent?"

There is a typographical error in this tattoo. In the Chinese language, writings are written either using the Traditional characters set or the Simplified characters set, but not mixed use of both sets. In this tattoo, the third character "長" and the first character "鷹" are written in traditional form, whereas the second one "击" is written in simplified form. (The last character has the same form in traditional and simplified character sets) Inconsistency like this results in confusion for readers.

• The correct rendering of the full set in simplified form should be:

  鹰击长空

• The correct rendering of the full set in traditional form would be:

  鷹擊長空

• Compare to the sequence on the tattoo:

  鷹击長空

Origin

This is the original handwriting (calligraphy) of this poem.	Ch'ang-sha 1925 Standing alone in the autumn cold: The Hsiang flowing northward, Orange Island, the cape. I see thousands of hills in crimsoned view, The woods piling up in deep-dye; The mighty stream, in its gleam of jade, One hundred barques racing by. Eagles high up, cleaving the space, Fish gliding above shallow ground; Ten thousand creatures, under frosty a sky, all fighting for freedom. In the waste's dreariness brooding, I ask the blue space without bonds: Who masters fate's rise and descent? Once I came here with a hundred companions, Vivid the months and years yet, filled with pride. Schoolmates we were, and young altogether, Upright and honest, in the bloom of our lives; Impetuous students, full of enthusiasm, We cast all restraints boldly aside. Pointing to China, its mountains and rivers, Setting the people afire with our words, And counted for muck all those ranking high. Do you still can remember: How, venturing midstream, the oars lashed the waters And the waves yet staying the flight of our boats?	Original handwriting (calligraphy) of this poem with "ying ji chang kong" highlighted.
This poem is one of the most popular poems by Mao. It is widely used as an exemplary poem in the Chinese high school textbook in the People's Republic of China. Most Chinese high school students in that country should be able to recite this poem, or at least part of it.

Trivia

• The 1st Season DVD interview with Matthew Fox mentions that these tattoos were his before the show. The producers first considered putting make-up over them, but later decided they fit in with the show and kept them.
• The fact that the tattoos received an entire episode to explain them has led to widespread derision of the tattoos among the Lost fanbase. Damon Lindelof and Carlton Cuse regularly joke about the tattoos in interviews, often joking another episode will focus on them or that they hold deeper importance.
• Also on the 1st Season DVD, during the episode "House of the Rising Sun", at about 40:06, when Jack leads a group to the cave, his tattoo is clearly visible on his right shoulder, indicating that the film negative was most likely reversed in editing.
• The literal translation of the tattoo, "Eagles high, cleaving sky", is echoed visually in "Stranger in a Strange Land" by the scene of Jack flying his kite.
• In "Lockdown" Sawyer asks Jack if the tattoos were made in Phuket, but he ignores the question.
• In real life, 5 in the tattoo is a tribute to Matthew Fox's days as a star on FOX's "Party of Five".^{[source needed]}

Unanswered questions

• The origin of the Chinese characters has been explained, but what is the origin of the rest of the tattoo?
• Why is the tattoo in Chinese, rather than Thai?