Sorry, I misunderstood you. I thought you meant the tech description in the tutorial. I have checked and the armour text in-game is out of date so I'll change it for the next DB release. However, as I keep saying, the most up to date information is in the Tutorial and FAQ forums. If you had read the tutorial you would have seen the following information on armour (shown below):
"Armour Rating is the thickness of the armour and can be increased or decreased by clicking the small arrows to the right of this box.
Armour Area is the surface area of the ship based on the assumption it is spherical in shape
The Armour Strength Required is equal to (Surface Area / 4) rounded up. Armour sufficient to meet this requirement is automatically added to the design as it gets larger. If you increase the thickness of the armour then each extra 'layer' is added to the previous one. As the total size of the ship and therefore the total surface area increases with each layer of armour, each additional layer will be cover a greater area and therefore require greater strength than the previous one. Each type of armour in Aurora has a different strength rating per hull space (HS) so as tech increases you will need less hull space dedicated to armour to meet the Armour Strength Required. As less armour also means a smaller ship, extra layers of armour will also be smaller.
For example, at the moment you have the technology for Duranium Armour, which has a strength per HS of 5. The armour area is 14.1. Dividing by 4 gives us a Required Armour Strength of 3.525. As Duranium has a strength per HS of 5, we need 3.525/5 HS of armour, which is 0.705, rounded to 0.7. As you can see on the design, 0.7 HS of Duranium Armour has automatically been allocated. If you had High Density Duranium Armour, which has a strength of 6 per HS, you would only need 3.525/6 = 0.6 HS of armour. Obviously this make little difference at the moment but as ships get larger and armour gets stronger, it can make a significant difference. Try increasing the Armour Rating to 2. The ship is now slightly larger and there are two layers of armour so the surface area has increased to 16 and the armour strength to 8. Duranium Armour is armour strength 5 so we need 8/5 = 1.6 HS of armour. Put the Armour Rating back to 1 for now. You don't really need to remember any of the details. Just remember that increasing the armour thickness or increasing the size of the ship will increase the amount of armour required and researching new armour tech will reduce the amount of armour required for future designs.
Armour Columns is the 'width' of the armour. The armour system in Aurora combat is similar to that of an old FASA game called Interceptor. The armour is represented by a block of 'boxes' with the width based on the size of the ship and the depth based on the thickness of the armour. Each weapon type has a damage template which determines which armour 'boxes' are damaged. Missiles tend to crater the armour while lasers cause narrower but deeper damage. Some weapons, such as railguns, have a high rate of fire and cause more overall damage than lasers but because that damage is split among many small hits, they tend to sandpaper armour rather than penetrating as a laser does. Any damage hitting in a location where all the armour has been destroyed will penetrate and cause internal damage. It is possible even for a well armoured ship to get unlucky and receive several hits in the same location, which will result in armour penetration and internal damage. That internal damage could even set off a string of secondary explosions, so a Hood style catastrophe is possible. Equally, if a ship has hits distributed all over the armour and doesn't lose any key system or suffer secondary explosion, it can withstand quite a lot of punishment"
Steve