事

1. Origins, structure, and basic meaning

• Structure: The formal noun 事 (こと) packages an event, act, or situation as a thing or matter.
• Basic usage: It can refer to an event in あった事 or nominalize an action after a verb, as in 歩く事.

2. Common pitfalls and similar expressions

• An event noun and nominalization
  • Sentence structure distinguishes a concrete event from the nominalizing function attached to a preceding clause.