google “eve tanking”
click on : Tanking - EVE University Wiki
read " Armor tanking
Armor tanking emphasizes the use of Low slot modules to increase armor hit points, resistance to damage, and gain the ability to repair damage taken by armor. Regardless of the approach taken to armor tanking, understand that armor on T1 hulls has an inherent weakness to Explosive damage, and usually a mild weakness to Kinetic damage, and thus you should plan your resistance modules accordingly.
Armor-tanked ships generally have much stronger buffers than shield-tanked ships. This is aided by Armor having near-universally higher base damage resistances than shields (albeit with the opposite order of strengths and weaknesses), and several modules which increase armor hitpoints and resistances which have no shield equivalents.
Armor Repairers are more capacitor-efficient than Shield Boosters (in terms of HP recovered per GJ Capacitor used), and they repair large amounts of HP on every cycle. However, they also cycle very slowly, meaning that they effectively restore less HP per second than shield boosters; and the HP gained is applied at the end of the module cycle (rather than the beginning as it is for shield boosters), meaning that a pilot must anticipate when the repairs will be needed several seconds in advance.
Armor tanking modules generally do not use nearly as much CPU as shield tanking modules. (Some armor tanking modules even consume no CPU at all!) However, Armor Plates and Armor Repairers use much, much more Powergrid than any shield-tanking modules. Furthermore, because armor tanking modules take up Low slots, they leave their ship’s Mid slots free for capacitor modules, Electronic Warfare modules, and damage application modules, which gives armor-tanked ships much more utility and versatility than shield-tanked ships. However, in exchange, because armor takes up low slots, and damage-increasing modules also take up low slots, armor-tanked ships generally have lower potential damage output than shield-tanked ships.
Once a ship’s armor is depleted, only its hull stands between it and death. This means that, in theory, armor-tanked ships have smaller safety margins than shield-tanked ships. However, this is also fact that Gallente ships are well aware of and, in fact, designed around: Gallente ships commonly feature bonuses to local armor repair modules, and Gallente ships also have the thickest hulls of any ships.
Armor Plates have a unique penalty to them: increased ship mass. This penalty reduces ship agility (acceleration and alignment time), and reduces the speed bonus gained from Propulsion equipment. Armor Rigs also (usually) reduce ship max speeds. As a result, heavily armored ships tend to be significantly slower than heavily shielded ships."
edit: Tipa riot had already linked it, my bad