International Humanitarian Law is meant to inter alia protect persons from the savagery of warfare. These protected persons are described in the four Geneva Conventions and their Additional Protocols. Broadly they are categorized here for purposes of convenience as Combatants/other legitimate participants in hostilities, Civilians and the Humanitarian Core. Each is examined briefly.
Combatants and other legitimate participants in hostilities
Combatants and those who are considered legitimate participants in hostilities are that group of individuals that get protection in special circumstances. These circumstances include when they are injured or sick (Geneva Convention I, article 12), shipwrecked (Geneva Convention II, article 12) or fall into the hands of the enemy (Geneva Convention III, article 4). Other than that, they can be targeted as legitimate military objectives and their deaths are lawful (Additional Protocol I, article 43).
Combatants are members of the armed forces of a Party to the conflict excluding medical personnel and chaplains (AP I, article 43). Article 13 common to GC I and II provide protection for those who are not necessarily members of the armed forces Party to a conflict thus the other legitimate participants in hostilities.
Such include militias, volunteer corps and organized resistance movements provided they observe the listed rules under clause 2 paragraphs (a)-(d). It also includes people who accompany the armed forces such as war correspondence, supply contractors etc. Finally those who spontaneously take up arms on approach of the enemy without having time to organize themselves into regular armed units (levee en masse) are also considered for protection.
Those who parachute from aircrafts in distress are also included under article 42, AP I. They are to be allowed to reach the ground of territory controlled by the adverse Party to the conflict and given an opportunity to surrender.
This group is considered to be the most vulnerable. They are thus protected at all times and in all circumstances.
They are protected under article 4 & 13 of Geneva Convention IV, AP I arts.10 & 50 and AP II art.7. Article 4 confines the term protected persons as those from a Party to the conflict, who is a signatory to the convention and is conducting hostilities with the Party in whose hands the civilians fall into.
Article 13 covers the entire population of a country in conflict. It (GC IV) does not define who a civilian is but article 50 of AP I does this by describing them as what they are not. It refers one to GC III article 4 A (1); (2), (3) and (6) as well as Article 43 of AP I. There are also special categories of civilians recognized such as refugees and stateless persons (GC IV, art. 44 & AP I, art.73), women and children (GC IV, art.50 & AP I arts.76-77) and journalists (AP I, art.79).
This group is concerned with the alleviation of pain and suffering during armed conflict. They include medical personnel, religious personnel and humanitarian relief personnel. They are protected by the conventions and Additional Protocols. For detailed information see GC I arts.24-26, GC II arts.36-37, GC III art.33, AP I, arts.15 & 71(2) & AP II art.9.
Please note that this is just a mind map on protected persons and that one should read the texts of the Geneva Conventions and their Additional Protocols to come up with a comprehensive list.