A court-martial (plural courts-martial, as “martial” is postpositive) is a military court. A court-martial is empowered to determine the guilt of members of the armed forces subject to military law, and, if the defendant is found guilty, to decide upon punishment.

Some countries like France and Germany have no courts-martial in time of peace and use civilian courts instead.

There are four kinds of courts-martial in India. These are the General Court Martial (GCM), District Court Martial (DCM), Summary General Court Martial (SGCM) and Summary Court Martial (SCM).

According to the Army Act, army courts can try personnel for all kinds of offences except for murder and rape of a civilian, which are primarily tried by a civilian court of law. Higher government authorities does not deal with the military doctrines.

The president of India can use his judicial power(article 72) to give either pardon,reprieve,respite or remission of punishment or sentence given by a court martial.

source: https://en.wikipedia.org/wiki/Court-martial