界 (Kanji for the world)

Onyomi

KAI

Farmers used big KITEs, with their farm's name printed on the underside, to introduce their rice to the world!

世界(せかい)	the world ★★★★★ 世 (society) + 界 (the world) = 世界 (the world) the world, as in "biggest in the world!" "fastest in the world!"
芸能界(げいのうかい)	showbiz ★★★☆☆ 芸 (art) + 能 (talent) + 界 (the world) = 芸能界 (showbiz)
境界(きょうかい)	boundary ★★☆☆☆ 境 (border) + 界 (the world) = 境界 (boundary) means border or boundary of property (80% the same usage as さかい　（境） , but a bit more formal). BOTH 境　and 境界　are often used in the figurative sense - like "This film pushes the envelope of good taste" or "His art blurs the boundary between painting and sculpture". Also used in science.
xxx 界(かい)	the world of xxx ★★☆☆☆ Suffix meaning, 'the world of XXX', as in 政界(せいかい) (the world of politics) or. . . . 芸能界 (げいのうかい) (the world of show biz)