What Does By Mean?
By is a preposition with several meanings: near or beside ("sit by the window"), through the action of ("a book by Hemingway"), or before a deadline ("finish by Friday").
By functions as a preposition / adverb.
What Does Buy Mean?
Buy is a verb meaning to purchase or acquire something in exchange for money. Its past tense is bought.
Buy functions as a verb.
By vs Buy: Key Differences
| By | Buy |
|---|---|
| Preposition (near, through, before) | Verb (to purchase) |
| Never changes form | Conjugates: buy, buys, bought, buying |
| "Stand by the door" | "Buy a new car" |
Examples of By in a Sentence
- The café by the river has great coffee.
- This painting was created by a local artist.
- Please submit your report by 5 p.m.
- She walked right by without noticing me.
Examples of Buy in a Sentence
- I need to buy groceries after work.
- They bought a new house last spring.
- You can buy tickets online or at the door.
- He decided to buy her a birthday gift.
How to Remember the Difference
If you can replace the word with "purchase," use buy. If you can replace it with "near" or "before," use by.
Common Mistakes
| Incorrect | Correct | Why |
|---|---|---|
| I want to by a new phone. | I want to buy a new phone. | Purchasing requires the verb 'buy.' |
| The store buy the park is closing. | The store by the park is closing. | 'By' means near in this context. |
| Finish the assignment buy Monday. | Finish the assignment by Monday. | 'By' indicates a deadline. |
If you are unsure which word fits, try Rephrasely's free grammar checker to catch errors instantly.
Frequently Asked Questions
What about 'bye'?
'Bye' is short for 'goodbye,' a casual farewell. It is different from both 'by' (preposition) and 'buy' (verb). See our page on by vs bye for more.
What does 'by and large' mean?
'By and large' is an idiom meaning 'generally' or 'on the whole.' It uses the preposition 'by,' not 'buy.'
Is 'buy-in' one word?
'Buy-in' (with a hyphen) is a noun meaning agreement or support. 'Buy in' (two words) is the verb phrase meaning to purchase a share of something.