Armor, like most other specialized fields of knowledge, has its own jargon. This is a short list (probably to get bigger) of common terms, acronyms, and other such things that mean nothing to the layman but are often encountered in anything even remotely concerning armor.
PARTS OF A TANK
Armor - This either refers to a tank itself or the armor plating on a tank that protects it from damage. Defensive armor is all about thickness--if it is thick enough, it will protect the tank from whatever is hitting it. Sloped and curved armor is superior to boxy armor for exactly this reason--having sloped or curved armor forces opposing direct fire to come in at an angle to the armor plate, forcing it to try and penetrate thicker armor. Having box-like armor, which was common early in the war, causes incoming fire to strike perpendicular to the armor plate, giving it the least amount of thickness and thus resistance. The problem with armor is that anything strong enough to pierce it will matter-of-factly demolish whatever is inside the shell. This is why Angriff! is concerned only with armor penetration and not internal damage effects of any sort.
Bogies
Bow Gun - A weapon mounted in the front (bow) of a tank. This is usually a medium machine gun of some sort, although on turretless tank destroyers the bow gun is usually the main gun as well. Some turreted tanks, especially the British Churchhill, also had cannon mounted in the bow for some reason or another.
Crew - The most important component of a tank are the hapless saps stuck inside of it. Most tanks in WWII had five crew positions (driver, assistant driver/bow gunner, main gunner, main gun loader, and commander) but later and lighter tanks lacking a bow gun usually had four. Some tanks had crews up to ten (usually old tween-war tanks) and others had crews of three (light scout tanks).
Coaxial-Mount Gun - A machine gun in the turret aligned with the main gun so it points in the same direction (sharing an axis, thus coaxial). There are times when the main gun is simply too big to attack a target at short range (the broadside of a truck, for example) and so the coaxial gun was a secondary weapon for turret gunners.
Cupola - A raised portion of a turret, usually independently rotatble of the turret (think of a mini-turret on a turret) and armed with a machine gun. The most notable example of this is on early M3 Grant/Lees.
Hull - The body of the tank, containing the engine, transmission, ammunition, and most of the crew. While well armored on the front, the sides and rear of the hull are armored less well (never back up into a fight!) while the top and bottom are the worst-armored portions of a tank (neither angle should really get shot at very much except from artillery and guys in holes). Damage to the hull is bad and most often lethal.
Main Gun - The biggest gun on the tank, usually mounted in a turret. Usually a rifled light artillery piece, the main gun can also be as paltry as one or two fire-linked machine guns on very light tanks. Multiple large main guns, despite anything that playing too much Red Alert would tell you, was never effective enough to be used. The only exception I know to that rule is the Ontos, a Greek tank that had eight 75mm recoiless rifles (think Überbazookas) on a turret.
Periscopes - When all the hatches are closed on a tank, vision is sorely limited. On later tanks, the most common way to see out of the armored shell were prism periscopes, which you can buy nowadays from the back of science magazines. This method had the main advantage of protecting the crew from enemy fire and the twin disadvantages of limiting the crew's field of view and being excellent targets for good snipers.
Pintle Gun - A machine gun on a flexible mount on top of a turret. Used by the tank commander ostensibly for anti-aircraft purposes, the pintle gun usually found use as an anti-infantry weapon to the sides and rear of the tank. It was not a popular weapon as the tank commander had to be halfway out of the protection of the armor to use it.
Road Wheels
Sponson - Secondary turrets on the side, rear, or front of a tank, mounting either cannon or machine guns. Common in the ancient tanks of WWI, by WWII the only common tank with an honest (forward) sponson was the M3 Grant/Lee. By the end of the war, sponson were considered obsolete as tanks loaded with heavy weapons in multiple sponson were too slow to be effective.
Tracks/Treads - The typical drive system of a tank, the treads, consist of interlocking metal plates that form a closed loop that, once put around rollers, provides an excellent all-terrain system. Tanks operate through differential steering--each tread is driven separately and turning a tank is achieved through the difference in the motion of the treads. If the left tread is moving faster than the right tread, the tank will turn right as it pivots along the slower-moving right tread. If the right tread is the faster, the reverse happens.
Turret - A rotatable armored platform, usually containing a tank's main gun, mounted squarely on the top of the hull. It allows a tank to move in one direction yet fire in another, giving tanks yet another advantage in maneuverability and combat effectiveness.
Vision Slits - The most natural way to see out of a closed box is to cut some holes. Vision slits are no more than holes in the armor shell that allow the crew inside to see outside. Vision slits are far more dangerous than their alternative, periscopes, because no armor means no protection. A common way for infantry to melee a tank was to run up to any available vision slit and pop in a grenade or spray small-arms fire into it. This was not conducive to the crew's health.
TANK STRATEGY
Blitzkrieg - German for "lightning war," blitzkrieg refers both to their lightning campaign across the European continent as well as their primary offensive combined-arms strategy. After air superiority was attained, low-level and dive bombing would destroy masses of defenders and disorient the rest, who are then overrun by armor. "Mopping up" and securing the area was left to infantry.
Buttoning Up - Out of combat, a tank operates with its hatches open in order to be more efficient. However, because open hatches make heavy armor pointless, the hatches are closed and the crew reverts to looking through vision slits or periscopes to keep an eye on the outside world. The process of closing the hatches is called Buttoning Up, a tank thus closed is called Buttoned Up. Due to a lack of peripheral vision, buttoned-up tanks are inefficient in combat because the driver has to constantly swerve in order to see the area. In modern times, the Israeli tank force orders its tank commanders to keep their hatches open so they can peer out and direct the tank better. The Israelis have one of the most efficient tank forces in the world, but they also have one of the highest per-capita tank commander casualty rates in the world to pay for it.
Flanking - Strategically and tactically, flanking refers to the concept of attacking an enemy in his sides or rear. Any force is always strongest at its front, because that strength is what gives said force any "direction" at all. It is silly and wasteful to attack an enemy at its strongest point, so the logical thing is to attack the enemy where it is weaker, namely the sides and rear. In short: flanking is good but being flanked is bad.
Formation,
Wedge - A wedge formation is the universal standard for the forward attack.
One tank, usually the lead tank (with the platoon commander in it) is in front with the
other two tanks in the platoon flanking it to the left and right, forming a
triangle. The front tank will attack targets ahead of the platoon, the left tank
will attack targets to the fore-left and the right tank will attack targets to the
fore-right.
Formation,
Bell (Inverted Wedge) - Less common than the wedge formation, an inverted wedge is
usually used in retrograde or when a volume of firepower needs to be brought straight
ahead.
Formation,
Echelon Left - Echelon left formation is where the tanks form a straight line with
each tank being slightly behind and to the left of the tank before it. Echelon
formations are used both in strafing attacks against the enemy and as a way to reorient
one's force while still maintain a coherent front against the enemy.
Formation,
Echelon Right - Echelon right formation is identical to echelon left except each
tank is behind and to the right of the tank preceeding it.
Formation,
Wall of Steel - A Wall of Steel formation is where all the tanks move forward in a
line, side to side, and takes its name from the proverbial oncoming wall of tank-chassis
steel. A Wall of Steel, although impressive to neophytes, is easily disrupted from
the sides and is practically artillery or (especially) air-power chow.
Hull Down - Hull down is when a tank, usually because it was entrenched before battle, is situated so only the top of it (i.e. the turret and main gun) are visible to the enemy. This allows the tank to attack the enemy with less of a chance of being hit, thanks to its cover.
Melee - Close range combat of any kind. For tanks, this usually involves infantry doing their damndest to stop them. Heavily armored tanks with periscopes have less to fear in melee situations than would an unarmored truck or an open-topped tank destroyer like an M18.
Retrograde - The quintissential " fighting fall back," a retrograde is a measured movement away from the enemy while still firing. While most often used to disengage from combat with maximum order and minimum casualties, it can also be used to lure enemies into ambushes and the like.
THE MEASUREMENT OF MAIN GUNS
"75mm L42!" I hear you cry. "What, in the name of all things good and decent, does that mean?" Never fear, I am here to help. Main guns are measured in two dimensions--width and length. Nothing too hard there. The width of a main gun is obviously its caliber, which is usually measured in millimeters. So the caliber of a "75mm" gun is, well, 75 millimeters. Some sources will use centimeters, at which it will read "7.5cm" or something similar. As there are ten millimeters to a centimeter, there is no real difference. The length of the main gun is measured as a multiple of the gun's caliber. An "L42" gun, therefore, has a length that is 42 times longer than its caliber. In the case of a 75mm L42, its length would be (42 x 75mm = 3150 mm / 1000mm per m = 3.15m) 3.15 meters.
"Why can't they just say '75mm L3150' or something?" is the response. I don't know. Find someone who knows something about ballistics and ask them, but I do have a reasonable guess--a weapon's strength is dependent on both its caliber and barrel length (up to a limit, of course). A larger-caliber shell has more mass to fling about, while a longer barrel increases the muzzle velocity of the shell (by allowing the exaust gases of the exploding propellent to act upon the shell longer). There must be a relationship somewhere, but I'm really not sure about the math involved.