Denn, weil & deshalb
Und, aber, oder and denn join clauses without sending the verb to the end. Weil does send it to the end. Deshalb means therefore and occupies a sentence element: Deshalb + finite verb + subject.
Understand the idea
Connectors show relationships between ideas, but they belong to different word-order groups. Some join two main clauses, some introduce subordinate clauses, and some are adverbs occupying a main-clause position. The meaning and the word-order category both matter.
Build it step by step
Und, aber, oder and denn do not turn the following clause into a verb-final subordinate clause. Weil does. An adverb such as deshalb can stand first in a main clause; the finite verb then follows directly. Punctuation helps separate the clauses, but it does not replace the word-order decision.
See it in a sentence
Ich bleibe zu Hause, denn ich bin krank.
Ich bin müde. Deshalb gehe ich schlafen.
A useful memory aid
Group connectors into three columns: main-clause joiners, verb-final introducers, and sentence adverbs. Learn one complete example for each column.
A common trap
Do not use weil and deshalb with the same word order. Deshalb is a main-clause element, not a subordinating conjunction.