Enfilade/defilade fires, direct fire, indirect fire, fire suppression, final protective lines.. there's a few different types, and it's impossible to be specific with a question worded so vaguely as this one is.
The aircraft mounted machine gun was at first simply a ground machine mounted for a gunner to fire. All sides in WW1 used it. The first successful machine gun fired by a pilot was the Lewis machine gun on a special mounting attached to the top wing, allowing the gun to fire over the propellor.
The purpose of inventing the machine gun was to have better fire power during the wars to defends places and win positions and the war.
A cannon is a direct fire weapon as used on tanks. A machine gun is rapid fire weapon of a smaller caliber used by infantry or aircraft, and a howiitzer is artillery which uses a high angle of fire to project shells in a plunging manner on the target. In general, a cannon is 20mm or larger, a machine gun is 20mm or smaller and a howitzer is 75mm or larger.
Your machine guns in use in 2010 were still developed between the 1950s and 1980s, generally. A gas operated machine gun might fire anywhere from 500 - 1200 rounds per minute, depending on type. Weapons such as the M-134 Minigun can fire between 3000 - 6000 rounds per minute.
It was much easier to defend a trench because you were behing cover and camped in to your position unlike the attackers who were running across open plains and were constantly loosing men and getting shot down by machine gun fire.
You're probably thinking of strafing, which can be done with rockets, as well.
Heart attack
Yes, Machine Gun Kelly died on July 18, 1954
The Metal Storm is the World's fastest machine gun. It fires 1660 bullets in every second up to 1 million rounds per minute without having someone to crank it up. The Metal Storm can be an unmanned machine gun and can open fire automatically because the computer is operating the machine gun. No other machine gun in the World can fire as fast as the metal storm at that kind of firing speed. Metal Storm is one of the fastest machine gun in the World and can fire more bullets much faster than other machine guns. Metal Storm is not an actual machine gun. It is a volley gun. See the Related Question below for a better discussion of what a real machine gun is, and which has the highest rate of fire.
The aircraft mounted machine gun was at first simply a ground machine mounted for a gunner to fire. All sides in WW1 used it. The first successful machine gun fired by a pilot was the Lewis machine gun on a special mounting attached to the top wing, allowing the gun to fire over the propellor.
Machineguns could be set to fire at a high angle, giving long range plunging fire. That fire could be used much like artillery fire against a distant target that was the focus of an attack.
A machine gun nest is a fixed position where a machine gun crew sets up their weapon. It is generally well covered and difficult to attack all while giving the machine gun crew a good arc of fire in the desired direction. The idea is to be able to deliver fire power where you want it and to be hard to take over. A good nest can be devastating to an infantry unit if they are caught up down an alley or a bottle neck position with relatively little cover
The rate of fire may be anywhere from 200 to 6,000 shots per minute, depending on the gun. There is no one rate of fire for all machine guns.
The "Potato Digger" was not the slowest rate of fire weapon. The French Chauchat machine gun fired 240 rounds per minute
pull back the trigger and aim!
Fire a lot of bullets very quickly.
They both fire things called 'Bullets'