Short answers, pulled from the story.
Anti-tank warfare originated in 1916 following the first deployment of tanks on the Western Front in September of that year. Germany, as the only nation facing enemy tanks, was the first to develop viable countermeasures, including the 3.7 cm Rheinmetall cannon rushed to the front in early 1917.
The Munroe Effect is the principle behind shaped-charge anti-tank warheads, discovered accidentally by Professor Charles E. Munroe at the U.S. Torpedo Station in Providence, Rhode Island. A shaped charge creates a high-velocity jet of metal that penetrates armor hydrodynamically, allowing a projectile to defeat heavy armor without requiring the high muzzle velocity of a kinetic energy shell.
Germany developed three main approaches: the Geballte Ladung, a bundle of stick grenades used to destroy tank tracks; the 13 mm Mauser 1918 T-Gewehr bolt-action anti-tank rifle; and the 3.7 cm TaK Rheinmetall anti-tank gun, issued in 1917. Existing 7.7 cm field guns were also given special armor-piercing ammunition.
Soviet first-generation wire-guided missiles used by Egyptian forces inflicted heavy casualties on Israeli tank units in the 1973 Yom Kippur War, causing a major crisis of confidence for tank designers worldwide. The engagement demonstrated that a small infantry team with guided missiles could threaten even the largest and most expensive tanks.
The Soviet Ilyushin Il-2 Shturmovik was one of the two Soviet weapons built exclusively for anti-tank purposes in World War II and was among the most-produced aircraft in history. It carried two 23 mm cannons, unguided rockets, and 2.5 kg shaped-charge PTAB anti-tank bombs, and its armored airframe let pilots approach at very low altitude through small-arms and machine-gun fire.
The RPG-7 is a man-portable anti-tank rocket launcher developed by the Soviet Union from the German Panzerfaust 150 by way of the RPG-2. It became one of the most widely used anti-tank weapons in the world, favored by irregular forces for its simplicity and its ability to fire a range of warheads including thermobaric and tandem-charge HEAT rounds. It has seen combat in conflicts from the Vietnam War to present-day fighting.