by
🔊 Pronunciation
/baɪ/
📝 Preposition Type
Type: preposition
Core meaning: proximity, agency, and means – originally expressing nearness, extended to temporal deadlines and instrumental relationships
Can function as: preposition, adverb
📍 Spatial Meanings
next to, beside, near to (proximity without contact)
indicates location in close proximity to a reference point, typically within arm's reach or immediate vicinity
She sat by the window and watched the rain.
There's a small café by the station.
Come and stand by me.
past, going beyond a point
movement past a reference point, passing alongside
She walked by the house without stopping.
The bus drove by without seeing us.
Time goes by so quickly.
via, through a particular route
indicates the path or route taken to reach a destination
We came by the coastal road.
You can get there by going through the park.
Enter by the side door.
⏰ Temporal Meanings
not later than, before or at a specified time (deadline)
Please submit your assignment by Friday.
I'll be home by 6 o'clock.
The project must be completed by the end of the month.
during, in the period of (typically with parts of day/night)
I prefer to work by night.
By day he's a teacher, by night a musician.
Cats hunt by night.
Temporal Phrases
by now: at this point in time, considering what has elapsed
“She should have arrived by now.” “By now, everyone knows what happened.” “You should be used to it by now.”
by then: at that point in time (past or future reference)
“By then it was too late to change anything.” “We'll be finished by then.” “She had already left by then.”
by the time: when a particular moment arrives/arrived
“By the time she arrived, everyone had left.” “By the time you read this, I'll be gone.” “By the time we got there, the store had closed.”
by far: by a great amount, to a great degree
“This is by far the best option.” “She's by far the most qualified candidate.” “That was by far the worst experience.”
by chance: accidentally, without planning
“I met her by chance at the airport.” “Did you find it by chance or were you looking for it?” “We discovered the restaurant by chance.”
💭 Abstract Meanings
Agency means
expressing the agent (who does) or means (how done)
The book was written by Hemingway.
We traveled by train across Europe.
She succeeded by working harder than anyone else.
Agent passive: The house was designed by a famous architect., The theory was developed by Einstein., The decision was made by the committee., The problem was solved by the team.
Means transport: by car/bus/train/plane/ship/bicycle, by air/sea/land/rail, EXCEPTION: on foot (NOT by foot), EXCEPTION: in my car (when possessive, use 'in')
Means method: by doing something carefully, by checking every detail, by working together, by saving money each month
Means communication: by email/phone/text/fax/post, by letter, by word of mouth, EXCEPTION: on the phone (during call), over the phone (method)
Measurement difference
expressing the amount or degree of difference
She won by three points.
The price increased by 10%.
He's taller by two inches.
We missed the train by five minutes.
Multiplication division
expressing mathematical operations
Multiply 6 by 4.
Divide 20 by 5.
A room 10 feet by 12 feet.
Profits increased by a factor of three.
Standard criterion
according to a standard, rule, or criterion
By law, you must wear a seatbelt.
By my watch, it's already 3 o'clock.
By any standard, this is excellent work.
Judge people by their actions, not their words.
Unit quantity
expressing units or quantities in succession
We sold them by the dozen.
They're paid by the hour.
Take the medicine two tablets by two tablets.
The soldiers marched two by two.
Day by day, she grew stronger.
Authorship creation
indicating creator or author
A painting by Picasso.
A symphony by Mozart.
A novel by Dickens.
Software developed by Microsoft.
🔗 Complement Structures
Noun phrase
Structure: by + noun phrase
by the door by next Tuesday by a famous author by sheer determination
Articles: articles used normally EXCEPT with means of transport/communication (by car, by email) and in certain fixed expressions (by chance, by mistake)
Pronoun
Structure: by + pronoun (often reflexive)
by myself/yourself/himself/herself/itself/ourselves/yourselves/themselves by me/you/him/her/it/us/them (less common, usually passive agent) Stand by me. She did it all by herself.
Gerund
Structure: by + verb-ing
by studying hard by working together by being patient by not giving up
Clause
Structure: by cannot directly introduce a finite clause
💬 Fixed Expressions & Collocations
Idioms
“by the way” – incidentally, used to introduce a new topic or add information (informal to neutral)
“by and large” – generally speaking, on the whole (neutral to formal)
“by all means” – certainly, of course (granting permission) (formal to neutral)
“by no means” – definitely not, not at all (formal)
“by heart” – from memory, memorized (neutral)
“by mistake” – accidentally, unintentionally (neutral)
“by accident” – unintentionally, not on purpose (neutral)
“by chance” – coincidentally, without planning (neutral)
“by nature” – inherently, as a natural characteristic (neutral)
“by definition” – according to the meaning of the term, necessarily (formal to academic)
“by degrees” – gradually, little by little (formal)
“by the book” – according to the rules, officially (informal to neutral)
“by the same token” – similarly, for the same reason (formal)
Collocations
Verb + prep:
Obligatory: abide by (rules/decision), stand by (support someone/something), swear by (believe in strongly), go by (be known as/follow), judge by (evaluate based on), live by (follow principles)
Common: affected by, amazed by, confused by, disappointed by, fascinated by, impressed by, influenced by, inspired by, shocked by, surprised by, written by, designed by, created by, caused by, followed by, accompanied by, surrounded by, covered by, protected by
Adj + prep:
Common: accompanied by, amazed by, annoyed by, confused by, disappointed by, fascinated by, followed by, impressed by, shocked by, surprised by, unaffected by
Noun + prep:
Common: increase by (amount), decrease by (amount), reduction by (amount), rise by (amount), fall by (amount), difference by (amount), victory by (margin)
⚠️ Common Errors
❌ I go to work by foot.→✓ I go to work on foot.
'On foot' is the only correct expression for walking; 'by' is used with vehicles (by car, by bus) but not with walking
Common for: Romance languages (Spanish 'a pie', French 'à pied'), Germanic languages
Medium impact – understood but non-native impact
❌ I will finish it until Friday. / I will finish it by Friday.→✓ I will finish it by Friday. (deadline) / I will work on it until Friday. (continuous action)
'By' indicates a deadline (completion point), 'until' indicates continuation up to a point. Many learners confuse these.
Common for: Many languages use same word for both concepts (Spanish 'hasta', German 'bis', Chinese '到')
High impact – changes meaning significantly impact
❌ The book was written from Shakespeare.→✓ The book was written by Shakespeare.
Agent in passive voice must use 'by', not 'from'. 'From' indicates origin or source, not agency.
Common for: Languages where origin/agent use same preposition (some Slavic languages)
High impact – grammatically incorrect impact
❌ I go to work by the bus. / I came here by my car.→✓ I go to work by bus. / I came here in my car.
'By' + means of transport takes no article when referring to the mode generally. Use 'in/on' with possessive pronouns (in my car, on my bike).
Common for: Languages requiring articles with transport (Romance languages)
Medium impact – understood but incorrect impact
❌ I sent it by the email.→✓ I sent it by email.
Means of communication with 'by' takes no article (by email, by phone, by post)
Common for: Languages requiring articles (French, Spanish, German)
Low impact – understood but non-native impact
❌ She lives by herself alone.→✓ She lives by herself. OR She lives alone.
'By oneself' already means 'alone', so adding 'alone' is redundant
Common for: Literal translation from languages where both elements are used
Low impact – redundant but understood impact
❌ The house is by near the station.→✓ The house is by the station. OR The house is near the station.
'By' and 'near' both indicate proximity; using both is redundant
Common for: Emphasis patterns from other languages
Low impact – redundant but understood impact
❌ I learned English by myself self-study.→✓ I learned English by myself. OR I learned English through self-study.
'By myself' means alone/without help. For method, use 'through' or 'by' + gerund (by studying)
Common for: Confusion between 'alone' and 'method' meanings
Medium impact – awkward construction impact
❌ Day by day I improve. (incorrect word order in some contexts)→✓ Day by day, I improve. OR I improve day by day.
'Day by day' is typically set off by comma when at start, or placed at end of clause
Common for: Different word order rules in L1
Low impact – punctuation issue impact
❌ I must finish by Monday, so I have until Monday.→✓ I must finish by Monday, so I have until Monday to finish it.
While grammatically possible, learners often misunderstand that 'by Monday' means 'before or on Monday' (deadline) while 'until Monday' means 'up to Monday' (duration). The actions are different.
Common for: Conceptual confusion across many L1s
High impact – affects time management communication impact
⚖️ Contrasts with Similar Prepositions
By vs vs vs until
Spatial: not applicable
Temporal: 'by Friday' = finish before/on Friday (point); 'until Friday' = continue up to Friday (duration)
Abstract: different aspectual meanings
Key difference: 'by' indicates deadline (completion), 'until' indicates duration (continuation)
By vs vs vs with
Spatial: 'by' = proximity, 'with' = accompaniment
Abstract: 'by' = how something is done (method), 'with' = using what tool (instrument)
Key difference: 'by' indicates means/method/agent, 'with' indicates instrument/accompaniment
By vs vs vs near
Spatial: 'by' = right next to, 'near' = in the vicinity of (can be further)
Key difference: 'by' suggests closer proximity than 'near', more immediate adjacency
By vs vs vs beside
Spatial: both indicate adjacency, 'beside' emphasizes side-by-side arrangement
Key difference: nearly synonymous for location, but 'beside' is more formal and explicit about side-by-side positioning
By vs vs vs before
Temporal: 'by Monday' = on or before Monday; 'before Monday' = earlier than Monday, not on Monday
Key difference: 'by' includes the deadline time, 'before' excludes it
By vs vs vs next vs to
Spatial: both indicate proximity, 'next to' emphasizes immediate adjacency
Key difference: 'next to' is more explicit about immediate adjacency, 'by' can be slightly more flexible
🌍 Etymology
Origin: Old English 'bi, be' from Proto-Germanic '*bi' (around, about, near)
Original meaning: “near, in the vicinity of, around”