Several parts combine into one character.

引 adds one straight vertical stroke (丨) to 弓 (bow) — a picture of drawing the bowstring back. From that came "to pull, to draw, to lead." The vertical is the direction in which the hand draws the string.

Mandarin: yǐn, 3rd tone. 引起 (yǐnqǐ, to give rise to), 引导 (yǐndǎo, to guide), 吸引 (xīyǐn, to attract), 引用 (yǐnyòng, to quote). 万有引力 (wànyǒu yǐnlì) is Newton's universal gravitation.

Japanese: on-reading イン (in), kun ひ.く (hiku). 引く (hiku, to pull / subtract), 割引 (waribiki, discount), 引退 (intai, retirement), 引っ越し (hikkoshi, moving house). Japanese ひく ranges widely — to pull, to lead, to look up (in a dictionary), even to catch (a cold).

Korean hanja-sound "in": 引力 (illyeok, attractive force), 引用 (inyong, citation), 割引 (harin, discount), 牽引 (gyeonin, traction). It is the character of pulling, in physics and in everyday speech alike.

Memory aid: beside the bow (弓), a straight pulling line (丨) — the force drawing the string back.