by

Used to indicate the means or method by which something is done, the agent performing an action (especially in passive constructions), a deadline or point in time, a specific amount or degree of difference, or proximity (next to).

• The novel was written by a famous author. — Indicates the person who performed the action.
• She traveled by train to get there. — Describes the method of transportation.
• You must submit your application by Friday. — Sets a deadline.
• We won the game by a narrow margin. — Shows the extent of difference.
• He lives by the old mill. — Indicates proximity or location next to something.

When used as an adverb, 'by' typically indicates passing past something or being located nearby. Unlike its use as a preposition, where it directly links to a noun, as an adverb, it modifies a verb or adjective to suggest a relative position or movement without explicitly stating what it's next to. This nuance often means there isn't a single direct equivalent in other languages like Japanese; instead, the meaning is conveyed through contextual phrases describing the action of passing or the state of being close.

• A red car just drove by. — Means the car passed the speaker's location.
• She walked by quickly without noticing me. — Implies passing someone or something.
• The old man sat by, watching the children play. — Indicates being situated nearby or observing from a close distance.
• Time flies by when you're having fun. — Refers to the swift passage of time.