A Hand Grenade is any small bomb that can typically be thrown by hand. Generally, a grenade consists of an explosive charge, a detonating mechanism, and a firing pin inside the grenade to trigger the detonating mechanism. Once the soldier throws the grenade, the safety lever releases, the striker throws the safety lever away from the grenade body as it rotates to detonate the primer. The primer explodes and ignites the fuze (sometimes called the delay element). The fuze burns down to the detonator, which explodes the main charge.
Hand grenades are classified into several categories & types: fragmentation (frag), high explosive (HE), concussion, smoke, chemical and gas grenades are some examples. Explosive grenades are the most commonly used in modern warfare, and are designed to detonate after impact or after a set amount of time. Chemical and gas grenades are designed not to explode, but to burn or release a gas.
In Mortal Kombat
In the franchise, Hand Grenades are typically used as projectiles and/or as a means to effectively end an opponent's life. Stryker is most known for utilizing them in his moveset and Fatalities. In Mortal Kombat (2011), he not only makes use of it in his Second Fatality, but also toss a M67 hand grenade at his defeated opponent after winning a match, without doing a fatality. Technically, Stryker will always perform a Fatality because of this.
In Mortal Kombat X, Sonya Blade uses them in her Demolition variation, with the grenades visibly secured on her thighs. Kano also uses grenades in his Cybernetic variation, but his other variations also affect his grenades visually by giving them a differently colored glow. Such as blue for Cutthroat and yellow for Commando. Two other kinds of Hand Grenades can be seen in the Black Dragon Faction Kills. Erron Black, also makes use of Sand Grenades in his moveset, even having it utilized in one of his fatalities.