The first real military rank with command responsibilities, a Corporal is frequently responsible for leading infantry squads, work details, acting as assistant vehicle commanders, or administrative sections. The naval equivalent does the same thing, assisting a WarShip gunnery officer or naval work detail.
A corporal in the SLDF typically had to serve for a year, which made them more experienced than their House counterparts. Typically this is the highest rank a soldier or sailor would reach. Their rank insignia was similar to that of a Private, but had the top and bottom sections colored green instead of white.
The rank insignia for a second SLDF corporal was the same as the first SLDF counterpart, but it replaces the green with black.
In the LAAF, like most militaries, a corporal will command an infantry squad or a heavy weapon element of an infantry squad.  Their rank insignia is sometimes known as the "Hunter's Point."
The LAAF, like the LCAF before it, also uses the rank of Senior Corporal. Soldiers with this rank are vehicle commanders and lead infantry squads. In addition, they are mentored by LAAF Sergeants to improve their command and leadership skills. A Senior Corporal's insignia is identical to a Corporal's, but has a black triangle.
In the AFFS, Corporals are the first level of command responsibility, heading up work details, infantry squads, and occasionally vehicle crews. Usually a Private is promoted to this rank after 12 months of service. This is also the first rank where the soldier begins to collect Death Compensation, a life insurance policy. Corporals wear two Scars as their rank insignia, color coordinated with their branch.
In the CCAF, a Corporal serves as an infantry squad leader or armored vehicle commander. The rank is also given to other specialists such as corpsmen and technicians. The device is a green bar, divided into three parts by brass lines. After Xin Sheng the rank was renamed to San-Ben-Bing.
In the FWLM a Corporal typically command infantry squads or serve as vehicle drivers and gunners. Occasionally they may pilot a BattleMech. If a FWLM Corporal pilots a 'Mech, they typically are called "MechWarrior" instead of Corporal. The FWLM Navy equivalent, Petty Officer, Second Class typically lead work details or head up small sections. 
A FWLM Corporal/Petty Officer Second Class uses three gold chevrons edged in purple as their rank insignia.
As is the case with most enlisted ranks, the Clans do not use the rank of Corporal.Point Commander is the first official level of command authority. However, in certain formations that consist of a large number of warriors (solahmna conventional infantry platoons or WarShip crews for example) or when dealing with Inner Sphere military forces, a clear chain of command is needed. As such a senior Warrior can be designated by the Point Commander as Point 1, Point 2, Point 3, Point 4, or Point 5. The lowest of these ranks, Point 1 and Point 2 could be considered equivalent to an Inner Sphere Corporal.
In the KungsArmé this rank is known by its Swedish name, Korpral. A Kavellrist is a Korpral who pilots a BattleMech. Korprals can also pilot AeroSpace Fighters. These soldiers wear a blue patch with an orange cross with small orange squares appearing in all corners as their rank insignia.
In the Taurian Defense Force, a Corporal is the leader of an infantry maniple, consisting of five troopers, or serves as a tank commander. Among the other branches, Corporal denotes a junior specialist, such as technician or corpsman. A silver ring with a red center serves as the rank insignia.
One step up from Corporal is Section Leader. Section leaders command a squad of two infantry maniples or lead an armor maniple of two tanks. Otherwise it denotes a senior specialist in the other branches. Section leaders wear a silver ring with a single "horn" on the left side.
The Hegemony Armed Forces, with their focus on re-creating the Roman Empire, do not use this rank. The Latin name for the soldiers who hold this rank in the HAF is miles probatus. An inverted silver chevron is their symbol of rank.
The Alliance Military Corps uses Protector for soldiers who command infantry squads and lead work details. Typically a Defender is promoted to Protector after a year's service. Their rank insignia is two of the Defender's green circles placed side by side.