Conjunction
A conjunction is two bodies at the same degree of the zodiac, the aspect of fusion, in which each planet takes on the other's business rather than merely commenting on it.
It is the strongest of the five major aspects and the only one that is neither easy nor hard by nature. Two benefics conjunct is a different event from two malefics conjunct, and the same angle carries both.
Classical practice reads a conjunction by condition rather than by angle: which planet is stronger by dignity, which is faster, and whether either is burned by nearness to the Sun. A conjunction to the Sun is its own subject, and combustion and cazimi both live there.
Frequently asked
Is a conjunction good or bad?
Neither by itself. It merges two planets, so its tone comes from which planets they are and what condition each is in.
How close do two planets have to be?
Usually within about eight degrees for the Sun and Moon and rather less for the others, which is what an orb sets.