Coordinating conjunctions (und, aber, oder, denn, sondern)

Und, aber, oder, denn, and sondern are the five coordinating conjunctions — the simplest way to join two complete sentences into one. They can also link smaller equal units, like two words or phrases (Kaffee oder Tee, klein, aber stark). Either way, the good news is that none of them touch word order at all: whatever came right after the conjunction stays exactly where it would be in a standalone sentence.

Quick shortcut: a coordinating conjunction doesn't count as "occupying" any position in the clause that follows it, so that clause's normal verb-second order stays intact — whatever would normally be first (the subject, or something else like a time word) still comes first, and the verb still comes right after it. This is different from subordinating conjunctions like weil or dass, which do change word order — a separate topic covered elsewhere.

The five conjunctions

• Ich lerne Deutsch, und ich lese jeden Tag. (I'm learning German, and I read every day.)
• Er ist müde, aber er arbeitet weiter. (He's tired, but he keeps working.)
• Kommst du mit, oder bleibst du hier? (Are you coming along, or are you staying here?)
• Sie bleibt zu Hause, denn sie ist krank. (She's staying home, because she's sick.)
• Das ist kein Fehler, sondern eine Absicht. (That's not a mistake, but rather intentional.)

Word order never changes

Compare a clause on its own with the same clause after a coordinating conjunction — the verb stays in exactly the same spot it would occupy in a standalone sentence (see Word order: the verb in second position):

• Ich lese jeden Tag. → Ich lerne Deutsch, und ich lese jeden Tag.
• Er arbeitet weiter. → Er ist müde, aber er arbeitet weiter.

The conjunction itself never counts as taking up the first position — something else still can. Morgen lese ich ein Buch still puts morgen first and inverts subject and verb, exactly as it would on its own: Ich lerne Deutsch, und morgen lese ich ein Buch. Nothing shifts to the end, and the coordinating conjunction never changes what the rest of the clause looks like. This is exactly why these five are called coordinating: they connect two equal, independent clauses side by side, rather than making one depend on the other.

Denn looks like weil, but behaves differently

Denn and weil both translate as "because," and both introduce a reason — but only weil pushes the verb to the end of its clause (a subordinating conjunction, covered separately). Denn is coordinating, so the clause after it reads just like a normal main clause:

• ✅ Sie bleibt zu Hause, denn sie ist krank. (normal word order, verb second)
• Compare (not covered here): a weil-clause would instead end in …, weil sie krank ist.

Sondern vs. aber

Both can mean "but" in English, but they aren't interchangeable. In the corrective use taught here, sondern appears after an explicit negation (nicht, kein), when the second part corrects or replaces the first — not just contrasts with it. (The fixed phrase nicht nur … sondern auch — "not only … but also" — is a separate pattern, not a correction, and isn't covered here.)

• ✅ Das ist nicht blau, sondern grün. (not blue, but rather green — a correction)
• ❌ Das ist nicht blau, aber grün. — wrong: once the first part is negated and the second part replaces it, sondern is required, not aber
• ✅ Er ist müde, aber er arbeitet weiter. (tired, but working anyway — a plain contrast, nothing negated, so aber is correct)

Comma rules

• Aber, denn, and sondern are always preceded by a comma: Er ist müde*,** aber er arbeitet weiter.*
• Und and oder don't require a comma, though one is allowed if it helps readability in a longer sentence: Ich lerne Deutsch*,** und ich lese jeden Tag* is fine, but Ich lerne Deutsch und ich lese jeden Tag is equally correct.

Common mistakes

• ❌ Das ist nicht kalt, aber warm. → ✅ Das ist nicht kalt, sondern warm. (a correction after a negation needs sondern, not aber)
• ❌ Er ist müde aber er arbeitet weiter. → ✅ Er ist müde, aber er arbeitet weiter. (comma is required before aber)
• ❌ Sie bleibt zu Hause, denn ist sie krank. → ✅ Sie bleibt zu Hause, denn sie ist krank. (denn doesn't occupy a position, so the subject still comes first, right after the comma — a weil-clause behaves quite differently, sending the verb all the way to the end instead)

Quick check

Choose the correct conjunction: aber, oder, denn, or sondern?

1. Ich trinke keinen Kaffee, ___ Tee. (correcting a negation)
2. Wir bleiben zu Hause, ___ es regnet. (giving a reason)
3. Er ist klein, ___ stark. (plain contrast)
4. Willst du Kaffee ___ Tee? (a choice between two things)

Key takeaways

• Und, aber, oder, denn, and sondern join two main clauses without changing word order — the verb stays in second position in each clause.
• Denn means "because," just like weil, but unlike weil it never pushes the verb to the end of its clause.
• Sondern replaces aber specifically when the second part corrects an explicit negation in the first part.
• A comma is always required before aber, denn, and sondern; it's optional (but allowed) before und and oder.