When you connect two sentences with a word like "therefore" or "although," the word order of subject and verb often doesn't change at all — the connector is simply added without disturbing the sentence's structure. This is exactly what makes German connectors (Konnektoren) deserve special attention, because every German connector belongs to one of three different grammatical categories, and each category forces a different verb position.
The first category is coordinating connectors like und, aber, oder, denn, and sondern: these aren't counted as a formal part of the clause's structure, so subject-verb order after them stays perfectly normal, as if they weren't there.
The second category is adverbial connectors like deshalb, trotzdem, außerdem, and dann: these words occupy the first position in the sentence themselves, and since the verb in German must always stay in second position, the subject gets pushed to right after the verb. This is called Inversion, and it's why the sentence becomes Es regnet, deshalb bleibe ich zu Hause — the verb bleibe comes immediately after deshalb, while the subject ich follows after it.
The third category is subordinating connectors (Subjunktionen) like weil, obwohl, damit, bevor, and nachdem: these open a full subordinate clause, and the rule is that the conjugated verb escapes all the way to the end, just as with relative clauses.
Meanwhile zwar ... aber expresses a concession — "true that X, but Y" — and nämlich introduces an explanation for something just said; it comes right after the verb, not at the start of the sentence.
This three-way split doesn't exist when a connector is grammatically neutral and never moves the verb. That's why the biggest mistake is treating every connector the same way: writing a verb-final clause after deshalb as if it were weil, or, conversely, forgetting Inversion after trotzdem or deshalb and putting the subject right before the verb (deshalb ich bleibe is wrong; the correct form is deshalb bleibe ich). The practical rule: before using any new connector, ask which grammatical category it belongs to, because its meaning alone doesn't tell you how to build the sentence around it.