本日

1. Origins, structure, and basic meaning

• Structure: 本日 is read as ほんじつ and is a formal noun or time adverb for the current day.
• Basic usage: Use 本日の受付 in an announcement and 本日だけ営業時間を短縮する for a one-day exception.

2. Common pitfalls and similar expressions

• Formality versus 今日
  • Both mean today, but 本日 gives notices, business communication, and official speech a more formal tone.
• Restriction from だけ
  • 本日だけ limits the shortened hours to today and does not imply that the change continues on other days.