Lesson

By

Uses of by

≈ 15 min 8 block(s)

Text

What does 'by' mean?

'By' is a small but very versatile preposition in English. It can show who performed an action, indicate how something was done, set deadlines, show location near something, or express measurements and rates.

Agent in passive sentences: The email was sent by the manager.
Method or means: We travel by train. / Send the file by email.
Deadline/time limit: Please finish the task by Friday.
Location/proximity: The office is by the river.
Measurement/rate: We charge $50 by the hour.
Expressions: by chance, by mistake, by the way

Table

Common Uses of 'by'

Use	Structure	Example
Agent (passive)	'be' + past participle + by + agent	The report was prepared by the marketing team.
Method / Means	by + noun (transport, communication, instrument) / by + -ing (method)	We will send the file by email. / By negotiating, we reduced costs.
Deadline / Time limit	by + time / date	Please submit the invoice by Friday.
Location / Proximity	by + place	Our office is by the river.
Measurement / Rate	by + unit	We bill clients by the hour.
Fixed expressions	by + noun	By the way, please review the agenda.

Tip

Key Rule: Check the function of 'by'

Decide what 'by' is doing in the sentence — agent, method, deadline, location, or measurement — and choose the correct structure.

Agent (passive): use 'by' before the doer. — The memo was written by Anna.
Method/means: use 'by' + noun (train, email, phone) or 'by' + -ing for method. — We improved results by testing new ideas.
Deadline: use 'by' + time/date to mean 'on or before'. — Send the file by Monday.
Location: 'by' often means 'next to' or 'near'. — The client met us by the entrance.

When unsure, ask: Is this the doer, the way, a deadline, or a place?

Example

Examples in context

The report was prepared by the marketing team.

Please submit the invoice by Friday.

We will send the contract by email.

Our office is by the main station.

Tip

Common mistakes to avoid

Be aware of frequent errors learners make with 'by'.

Mixing 'by' and 'until' for deadlines: 'by Friday' means on or before Friday; 'until Friday' means up to Friday but not after.
Using 'with' instead of 'by' to show the agent in a passive sentence: the correct preposition for the doer is usually 'by'.
Confusing method vs. agent: 'sent by email' (method) vs 'sent by John' (agent) — both use 'by' but mean different things.
Omitting 'by' in passive constructions: passive sentences generally need 'by' to indicate the agent when it is mentioned.
Using 'by' with wrong measurements: check whether the phrase needs 'per' (per hour) or 'by' (by the hour) depending on context.

If unsure, re-analyse whether 'by' refers to who, how, when, or where.

Quiz

Choose the correct sentence using 'by' to show the agent in a passive sentence:

Hint: Focus on passive voice: which preposition introduces the doer?

Quiz

Complete: The proposal must be approved _____ Monday.

Hint: Think about deadlines: 'on or before' which day?

Quiz

Choose the correct sentence that expresses means or method:

Hint: Look for the option that uses 'by' + method of sending.

Key Points

GrammarPoint

by

preposition CEFR B1 //baɪ//

A preposition showing agent, method, deadline, location, or rate.

The contract was signed by the lawyer.

Vocabulary

deadline

noun CEFR B1 //ˈdɛdlaɪn//

A fixed time or date by which something must be done.

The deadline for the report is Friday.

GrammarPoint

agent

noun CEFR B2 //ˈeɪdʒənt//

The person or thing performing an action (often introduced by 'by' in passive sentences).

The presentation was given by the CEO.

Vocabulary

method

noun CEFR B1 //ˈmɛθəd//

A way of doing something; a means or technique.

We approved the payment by bank transfer.

Expression

by the way

expression CEFR B2 //baɪ ðə weɪ//

An expression used to add a remark or change the topic slightly.

By the way, have you seen the updated schedule?

Expression

by the hour

expression CEFR B2 //baɪ ðə ˈaʊər//

Indicating a rate measured for each hour.

Consultants are often paid by the hour.