In the Alliance world, all player characters have a spirit and a body. These can be separated in some cases, normally via powerful ritual magic. At other times you may encounter a body without a spirit; examples would be a permanently dead corpse or a guardian golem.
Most effects target a body specifically. These include everything from alchemical gasses (which will only affect living creatures in most cases) to Web and Prison spells. In every case, unless stated otherwise, you should expect that all effects target the body only and will go away when someone becomes “dead.”
In addition to the above, a dead body is generally immune to any effect which doesn’t explicitly target the spirit. There are some effects which will specifically work on a dead body; these include Life, Create Undead, and Corrupt. There are some potent formal magic effects which will also target a spirit specifically and will thus work on a live (or dead) body so long as it contains a spirit. If your character is one of the fortunate (or unfortunate) subjects of some method which separates your spirit from your body, a Formal Magic effect which targets your spirit will not affect you if it strikes your body (subject to whatever caveats are on the methods used for separation). For example, a villain who is under a Controlled Spirit Store ritual whose spirit vessel is safely in their lair would call “No Effect” if their body is struck by a spirit-targeting effect like Shatter Spirit. However, they would still be affected by all body-targeting effects such as Sleep and Shackle.
Since a dead body can’t be targeted by most effects, if it’s being carried by someone it will count as a possession with all the corresponding results. When a Shun spell hits a character’s shield, they will still be affected by it; likewise they would be affected by a Shun spell that hits a body they are carrying. Only when an effect explicitly affects a spirit or dead body (Life, Obliterate, etc.) will a carried body take that effect