Lesson

And, but, or, so, because

Basic connectors

≈ 15 min 8 block(s)

Text

And, but, or, so, because — Connecting ideas

This lesson explains five common conjunctions used to connect words, phrases, and clauses. You'll learn their functions, typical placement, and how to use them correctly in professional contexts.

  • and — adds information or links similar ideas
  • but — contrasts two ideas
  • or — presents alternatives or choices
  • so — shows a result or consequence
  • because — gives a reason (introduces a subordinate clause)

Table

Conjunction Functions and Examples

Conjunction Function Example
and Add similar information; link items or clauses We reviewed the proposal, and we approved the budget.
but Contrast or show exception The project is on schedule, but the costs are higher than expected.
or Present alternatives or choices You can join the 9 AM meeting, or you can watch the recording.
so Show result, consequence, or conclusion Sales were strong, so the team received a bonus.
because Introduce a reason or cause (subordinate clause) The client canceled because they changed their strategy.

Tip

Key rule: Where to place conjunctions

Use the conjunction according to the relationship you want to show:

  • Use and/but/or/so between words, phrases, or two independent clauses.
  • Place a comma before and/but/or/so when you join two independent clauses (each with its own subject and verb).
  • Use because to introduce a reason; it usually connects a subordinate clause and does not require a comma before it.
  • If the reason comes first (Because + clause), place a comma after the reason when followed by an independent clause.

Check whether each part is an independent clause (subject + verb) to decide on comma usage.

Example

Examples in context

We prepared the slides, and we presented them to the board.

The vendor delivered the equipment, but one unit was damaged.

Would you like coffee or tea during the interview?

The client requested changes, so we updated the project timeline.

Tip

Common mistakes to avoid

Watch out for these universal errors when using conjunctions:

  • Omitting the comma when joining two independent clauses with and/but/or/so, which creates a run-on sentence.
  • Putting a comma between subject and verb when the conjunction connects shorter elements (e.g., words or phrases).
  • Using 'so' when you mean 'because' (they show different directions: result vs reason).
  • Using 'because' without a clause (e.g., 'because of' needs a noun; 'because' needs a clause).

Always identify whether you join two independent clauses or smaller units (words/phrases) to choose punctuation correctly.

Quiz

Choose the correct sentence:

Hint: Check punctuation when joining two clauses with a coordinating conjunction.

Quiz

Complete: They postponed the meeting _____ the CEO was unavailable.

Hint: Think about which word introduces a reason or cause.

Quiz

Which conjunction best completes the sentence? "You can accept the offer _____ negotiate a better package."

Hint: Which word offers a choice between two possibilities?

Key Points

Vocabulary

and

conjunction CEFR A1 //ænd//

used to connect words, phrases, or clauses that are similar or linked

Please review the draft and send your comments.

Vocabulary

but

conjunction CEFR A1 //bʌt//

used to introduce a contrast or exception

The deadline is tight, but we can finish on time.

Vocabulary

or

conjunction CEFR A1 //ɔːr//

used to present an alternative or choice

We can meet on Tuesday or Wednesday next week.

Vocabulary

so

conjunction CEFR A2 //soʊ//

used to indicate a result or consequence

We had a busy quarter, so management approved new hires.

Vocabulary

because

conjunction CEFR A2 //bɪˈkɔːz//

used to introduce the reason for something (introduces a clause)

She left early because she had a personal appointment.

GrammarPoint

coordinating conjunction

grammar_point CEFR B1 //kəʊˈɔːrdɪneɪtɪŋ kənˈdʒʌŋkʃən//

a conjunction that links equal grammatical units (words, phrases, or clauses), e.g., and, but, or, so

Use a coordinating conjunction to join two independent clauses with a comma.