Weapons and Modules

Laser falloff curve

DPS from Overcharged = DPS from Short Range = DPS from Rapid Fire; each has their own drawback with basically same result

FalloffThe distance at which a weapon’s damage starts to decrease. This varies by weapon.
Maximum rangeThe distance at which a weapon’s damage falls to zero. Also varies by weapon. Just because a weapon can fire out to a certain range doesn’t always mean you can actually hit with that weapon at that certain range.
DPSDamage Per Second – the damage you’ll be doing over time against a stationary target with continuous fire. Note that this does not always translate into real in-game experience.
sDPSSustained Damage Per Second – The damage you’ll be doing over time against a stationary target with continuous fire but also with reload pauses and distributor draw accounted for, for a slightly more realistic estimate. It still doesn’t always translate into real in-game experience.
Thermal DamageGenerated by all lasers, and partially by plasma accelerators and rail gun projectiles. Decreased by thermal resistance. Typically good against shields.
Kinetic DamageGenerated by all “cannons”, and partially by plasma accelerators and rail gun projectiles. Decreased by kinetic resistance. Typically good against unshielded hulls.
Explosive Damage Generated by missile weapons and mines. Decreased by explosive resistance. Typically good against modules, utility mounts and hardpoints.
Absolute DamageGenerated by plasma accelerators only. Bypasses resistance. Typically good against shields, hulls, and modules.
TTDTime to Drain – How long it takes you to empty the WEP Capacitor by continuously firing your current weapons. Does not always translate into real in-game experience.
Power DrawHow much power the weapon uses from your power plant, expressed in MegaWatts.
WEP DistributorThe capacitor that powers a closed loop cooling system whose job is to prevent your weapons from melting themselves with extended fire. An empty WEP Distributor results in Thermal Overload, where you can’t fire until WEP regains at least some energy.
Distributor Draw How much energy (either per second or per shot) the weapon uses from your WEP Capacitor which is part of your Power Distributor, usually expressed in MegaWatts. 
JitterThe weapon slightly shakes with each shot, resulting in a degree of unavoidable inaccuracy.
ReloadSome weapons have a specific clip size. After that clip is empty there’s a pause in which the weapon cannot be fired during which the clip is refilled. Varies depending on the weapon and on your engineering choices.
HardnessA value assigned to ship hulls to determine how much damage they take from various weapons. Higher hardness means that larger weapons (with higher Armor Piercing) are needed to do full damage against the hull.
Armor PiercingA value assigned to weapons to determine how much damage they do to ship hulls. Higher armor piercing means that a weapon can do more damage against ships with higher hull Hardness. 
HitscanThe weapon instantly strikes the target as long as you are aiming correctly.
ProjectileThe weapon’s shots travel at a specific speed. That travel time that has to be taken into account when aiming. Faster shots are easier to hit with but generally have lower damage.

What does Engineering Do?

Many weapons in Elite Dangerous are useful and effective as stock modules, but engineering helps to compensate for weaknesses in damage, range, distributor draw, and more. There are almost always trade-offs, so the basic effects are listed here. 

Engineering RecipeBenefits & DrawbacksUpsideDownside
Double ShotIncreased burst rate of fire, increased burst size, increased clip size, decreased maximum range. Frag cannons only.Tons of damage all at once.You run out of ammo very quickly.
EfficientLowers thermal load, lowers power draw, lowers distributor draw, moderate damage increaseFire longer with less heat and do more damage. Hard to go wrong with this one.There are higher damage options, longer falloff/range options, better AP options, etc. Weapons that are already efficient to begin with don’t benefit as much as you think.
High CapacityIncreases clip size, increases ammo capacity, small increase to rate of fire, increased power draw, increased module mass. Can double your available ammo. Good for utility weapons.Not a good option for damage in most cases. 
FocusedIncreases maximum range, moderately increased falloff, increases armour penetration, increases thermal load.Smaller weapons (low AP) do better damage against larger ships (high hull hardness).Falloff still exists, so your damage is pretty low at the maximum range. 
LightweightLowers module mass, lowers power draw, lowers distributor draw, lowers module integrityGives mass sensitive ships something to shoot with.Very low integrity – will break with one good hit.
Long RangeIncreases maximum range, increases falloff, increases power draw, increases module massMakes falloff nonexistent and range very long.Power draw can be punishing. Just because you have the range doesn’t mean you can hit with it. 
OverchargedHigh damage increase, increases distributor draw, increases thermal load, decreases clip size.Very high damage.The distributor draw penalty means you run out of WEP sooner, which means you gain heat faster than you think.
Rapid FireIncreases rate of fire, decreases reload time, decreases distributor draw, decreases damage per shot, adds jitterTons of hits per second. Reload time bonus is great.Per shot damage is lower, so single hits are lower DPS. Distributor draw is actually increased due to rate of fire. Jitter lowers your accuracy. 
Short RangeHigh damage increase, increases thermal load, decreases range.Very high damage.Heat can be damaging and will prevent consecutive shots on some weapons unless compensated for. Your DPS is zero unless you can stay within the weapon range.
SturdyIncreases module integrity, increases armour penetration, decreases thermal load, increases mass.Takes heat out of the equation for some high heat weapons.Other engineering options do most of these benefits better. 

Noteworthy Experimental Effects

Thermal Shock

Raises the target’s heat to a maximum of 99%. The target can raise it further by firing weapons, using SCBs, boosting, etc.
At least two weapons with this effect are needed to get targets to 99%, and you need to sustain fire to sustain the effect.
NPCs that overheat become slower, refuse to boost, and will only fire weapons with low heat. Basically, they’re sitting ducks. 

Thermal Vent

Changes the beam’s heat per second value to a negative and multiplies it.
With enough venting you can cool ships to 0% heat, counteract heat from other weapons, SCBs, etc.
Recommended engineering: Long range to use at range, Short range to vent the most heat possible, Overcharged if you can sustain the distributor draw, lightweight if you want a low mass weapon with low distributor draw but “normal” heat venting.
You can also put thermal vent on efficient beams to take away their remaining heat load (and if you don’t need anything else on the beam), but don’t expect a lot of heat to be vented. Huge beams are the major exception. 

Corrosive Shell

Increases damage done by 25% and increases armor piercing value by 20 for ALL weapons striking the hull while this is in effect.
Can be easily applied by a small high capacity multicannon or frag cannon, but it only works against hull. Save it for when shields are down.
There are very few situations where 25% more damage (plus whatever bonus damage you get for your increased AP) is worse than adding another weapon.

Inertial Impact

Adds 50% damage to burst lasers as kinetic damage, but also adds a lot of jitter.
If you have a ship that can stay in point blank range, you can do a lot of damage with this.
Regardless of primary engineering they’re pretty useless beyond 500m, so feel free to go with Short Range.

High Yield Shell

Reduces damage by 35% and also reduces rate of fire, but you do damage in a sphere at the point of impact on the hull and can affect any module that the sphere overlaps.
Has been nerfed like crazy over the years due to its ability to take out multiple modules in one shot (including power plants!), but it’s still useful with large and huge cannons.

Dispersal Field

Works exactly like chaff…makes gimbaled and turreted weapons wave around aimlessly.
If you have a chaff launcher and this, you can use one while the other is on cooldown.
Your shields will last longer because your enemies can’t reliably hit you. Just be careful for PA shots and fixed weapons. 

Feedback Cascade

Striking a ship using an SCB during the initial 5 second spinup will “cancel” a portion of the shield restoration depending on the amount of damage done.
This means that you want medium rails, not small, if you want to prevent most of an SCB from happening. 
Look for the (-) symbol to see if you hit correctly. 

Phasing Sequence

You do 10% less damage in general, but a hit on shields causes 10% of your damage to be done as absolute damage to the underlying hull regardless of distance falloff.
There are two types of weapons that do well with this…fast hitters and heavy hitters.
Cytoscramblers are actually both fast and heavy hitters! You’ll also only ever use them against shields, so no need to worry about them once the shields drop.