Several parts combine into one character.

紙 is a phonetic-semantic compound: 糸 (silk thread) on the left provides the meaning, while 氏 (shì, originally a clan name pictograph) on the right provides the sound (shi → zhi → ji / shi). The semantic logic is historical: before paper was invented, important texts in ancient China were written on silk. When the eunuch official Cài Lún (蔡倫) of the Eastern Han dynasty popularized true paper around 105 CE — manufactured from rags, hemp, and tree bark fibers — the new material was named with a character that still references silk, because the original writing surface was silk-based. The character preserves what amounts to a fossilized memory of pre-paper writing technology.

Korean reading "ji." 紙幣 (jipye, paper currency / banknote), 色紙 (saekji, colored paper), 壁紙 (byeokji, wallpaper), 新聞紙 (sinmunji, newspaper paper / used as packing material), 和紙 (hwaji, washi — Japanese traditional paper, occasionally referenced in Korean), 韓紙 (hanji, Korean traditional paper — handmade from mulberry bark, a UNESCO-recognized cultural heritage). 한지 is one of the proudest items in Korean traditional craft, used historically for documents, walls, and lanterns.

Mandarin zhǐ, 3rd tone (simplified 纸). 纸 (zhǐ, paper), 报纸 (bàozhǐ, newspaper — "report-paper"), 卫生纸 (wèishēngzhǐ, "hygiene paper" = toilet paper), 信纸 (xìnzhǐ, letter paper / stationery). To count sheets of paper in Mandarin, use the measure word 张 (zhāng): 一张纸 (yī zhāng zhǐ, "one sheet of paper"), 三张纸 (sān zhāng zhǐ, "three sheets"). The flat-thin classifier 张 covers all flat sheets including paper, photographs, beds, tickets, and tables.

Japanese on-reading シ (shi) — 用紙 (yōshi, blank paper / form), 新聞紙 (shinbunshi, newspaper paper). Most poetic Japanese term: 和紙 (washi, "Japanese paper") — handmade traditional paper that is one of Japan's defining craft traditions, central to calligraphy, origami, shoji screens, and bookbinding. Kun-reading かみ (kami, paper) — 紙 (kami), 折り紙 (origami, "folded paper" — the global cultural export), 手紙 (tegami, "hand-paper" = letter / personal correspondence). The compound 手紙 (tegami) is one of the most warmly nostalgic words in Japanese vocabulary, evoking the era of handwritten letters; modern email and text messages are 電子メール / メッセージ, never 手紙.

Memory aid: silk threads (糸) plus 氏 (just for the sound) — paper began life as silk, and the character preserves that origin even in the era of pulp.