The oracle-bone and bronze-script form of 广 depicts a simple lean-to shelter: a slanted roof line hanging off a cliff face, open on the sides — not a closed room but a broad overhang. The core image is space that extends horizontally outward from a fixed point, sheltered but unenclosed. Wideness, not depth.

The traditional form 廣 elaborates this: inside the 广 shelter sits 黄 huáng (yellow/brightness) as a phonetic hint, plus additional strokes suggesting the interior expanse. The simplified character strips all of that back to three strokes — the original cliff-overhang in its purest form.

From "wide open shelter" the meaning generalized to width, broadness, and extension in all directions — then, in the modern era, to broadcasting: 广播 (guǎngbō), literally "wide casting," the Chinese word for radio and television transmission.

广 (radical 53) appears in characters that involve structures, rooms, and broad covered spaces:

店 diàn (shop, inn) — a place of shelter where goods are kept. 床 chuáng (bed) — a piece of furniture within a shelter. 厅 tīng (hall, living room) — an open interior space. 座 zuò (seat, measure word for buildings) — a seated position within a structure. 庙 miào (temple) — a sacred shelter. 府 fǔ (prefecture, official residence) — the broad hall of authority.

The semantic thread is consistent: where you see 广 at the top-left of a character, look for a built space or something that happens under shelter.