公布 means 'to announce publicly' — it refers to the formal, official act of making information known to the general public or a large group. The character 公 (gōng) means 'public' or 'official', while 布 (bù) originally meant 'to spread' or 'to distribute', as in spreading cloth — here it metaphorically conveys the idea of disseminating information widely. Together, they emphasize openness and broad accessibility.

This verb is commonly used in administrative, educational, media, and organizational contexts: governments publish policies, schools release exam results, companies declare financial reports, and news outlets share major developments. It carries a neutral-to-formal register and implies intentionality, authority, and transparency — not casual sharing. It is rarely used for personal or informal announcements (e.g., telling friends about plans), where verbs like 告诉 (gàosu) or 宣布 (xuānbù) are more appropriate.