I haven't heard from Bromor Neckbeard in forever, either...
Ofcourse, I'm not around as much as I'd like, for that matter.
Modern "Armor":
Obviously, anything with bullet and/or shrapnel-proofing slapped on to it could be called "modern armour" (note spelling), but the term "Armor", in terms of it's use in the modern military, usually denotes a semi-specific tactical and strategic function of a given armor unit, or AFV. Infantry is used for tasks which are suitable to it, as is calvalry (which tends to mean helicopters, nowadays (aka "air assault"), but can also mean armoured cars), artillery, air support, etc., and the same can be said for Armor, as a term.
Armor can broadly mean any AFV ("armoured fighting vehicles", including an armoured Hum-Vee), but more specifically, "Armor" is just plain tanks. The "main battle tank", or medium tank (there are also light and heavy tanks, but it's called the main battle tank for a reason--it's what's mainly used, nowadays) is the most obvious and straightforward use of the term "armor", in the modern sense.
Tanks are designed for direct frontal (field) assault, and are good for gaining territory/destroying fieldworks, fortified front lines, and field fortifications directly (air support is less direct, and isn't useful for holding territory, in terms of campaign strategy), as well as combating enemy tanks and other AFVs (although this can often be better accomplished with anti-tank weaponry, such as the GAU-8), and holding territory, in combination with infantry.
You could make a case for heavily armed/armoured gunships, especially attack helicopters (specifically, the heavily armoured AH-64 Apaches and Mil Mi-24 Hinds), also being/functioning as "armor", but such units tend to function as close, airborne, ground support, which is what they were designed to do.
Tanks have defensive tactical capabilities, ofcourse, but aren't suitable for broad-spectrum defense, due to their maneuvaring limitations, and vulnerabilities. Offense, in the form of frontal, mobile, ground assault, is their main tactical purpose, with a grand strategic purpose of defeating the development of defensive front lines.
Armor is not artillery, although obviously any big gun can have artillery applications. Artillery is used for support, and may or may not be armoured. Artillery is also well suited to defensive strategies, where Armor may not always be (in urban settings, in terrain hazardous or impassable for tanks, etc.).
Armor is also not support, although many AFVs are used in a support role. Armor gets supported, just like infantry, and infact, infantry can support armor. Armor isn't intended to support infantry, as such, due to the presence of enemy armor, and also due to the mainly armor-combatting nature of a typical tank's main weapon. Furthermore, unsupported armor can be vulnerable to modern infantry, especially in close (urban) quarters.