The words that join words, clauses and sentences.
وَ is by far the most common word in the Qur'an. It simply joins, without implying an order of events.
وَ vs فَ vs ثُمَّ — وَ just joins; فَ adds immediacy or consequence ("so", "and then at once"); ثُمَّ puts a gap between the two events. أَوْ vs أَمْ — أَوْ offers a choice; أَمْ asks which of two, and follows a question.