The verb goes to the very end.

A Nebensatz is a subordinate clause — a clause that depends on a main clause and cannot stand alone. It is introduced by a subordinating conjunction (weil, dass, wenn, ob, obwohl, als, damit, bevor, nachdem, seit, bis, falls, …) and follows one strict rule: the conjugated verb moves to the very end of the clause. A comma always separates the Nebensatz from the main clause: "Ich lerne Deutsch, weil es Spaß macht." Nebensätze are how German expresses cause, condition, time, purpose, and indirect speech.

The conjugated (finite) verb goes to the very last position of the Nebensatz. In a main clause the verb sits in position 2 ("Er lernt Deutsch"), but a subordinating conjunction kicks it to the end: "…weil er Deutsch lernt." If the clause has multiple verbs (a modal + infinitive, or auxiliary + participle), the conjugated verb still goes last and the non-finite verb sits just before it: "…weil er Deutsch lernen muss" or "…weil er Deutsch gelernt hat".

The most common subordinating conjunctions are: weil (because), dass (that), wenn (if/when, present/future), als (when, single past event), ob (whether), obwohl (although), damit (so that), bevor (before), nachdem (after), seit/seitdem (since), bis (until), falls (in case), während (while), and the relative pronouns der/die/das/welche. Each of these sends the conjugated verb to the end. Coordinating conjunctions (und, aber, oder, denn, sondern) do NOT — the verb stays in position 2 after them.

Yes. German requires a comma to fence off every Nebensatz from its main clause — no exceptions, even after dass or weil where English usually omits it ("I think that he is right" vs. "Ich denke, dass er recht hat"). The same rule applies if the Nebensatz comes first: "Wenn es regnet, bleibe ich zu Hause." Skipping the comma is grammatically wrong, not just stylistically informal.

Separable verbs (aufstehen, anrufen, einkaufen, mitnehmen, …) split in a main clause: "Ich stehe um sieben auf." But in a Nebensatz they reunite as a single word at the end: "…weil ich um sieben aufstehe." The prefix snaps back onto the verb and the whole compound goes to the final position.

In a Nebensatz with a modal verb, the order at the end is "infinitive → modal" — the modal goes last. So "Ich muss Deutsch lernen" becomes "…weil ich Deutsch lernen muss." Two non-finite verbs (an infinitive and the modal) stack at the end with the modal in the very final slot. This trips up English speakers, who instinctively want "muss lernen" because that mirrors English word order.

When the Nebensatz comes first in a sentence, the Nebensatz takes "position 1" of the whole sentence — so the main clause must start with its verb (V2 rule). The result: the Nebensatz ends with one verb, the main clause begins with another, and they end up nose-to-nose across the comma. "Wenn es regnet, bleibe ich zu Hause." The comma sits between two verbs (regnet, bleibe). This pattern is one of the most distinctive sounds of spoken German.

No. Both translate to "because", but they belong to different categories. "denn" is a coordinating conjunction — the verb stays in position 2: "Ich bleibe zu Hause, denn es regnet." "weil" is a subordinating conjunction and triggers verb-final order: "Ich bleibe zu Hause, weil es regnet." Spoken German often blurs the distinction (you may hear "weil es regnet" used like "denn"), but in writing they are not interchangeable.