All this data is potentially out of date, and should be taken with a truckload of salt
Extremely valuable gas clouds have been discovered in the Pegasus constellation which have created a gold rush. ORE was quick to claim 'ownership' as the constellation borders its sovereign space, but the Serpentis and the Syndicate, as well as multiple entrepeneurs from the Gallente Federation, have all claimed their own piece of the pie. Inevitably collisions have occurred and the constellation has become a sort of 'warzone' between various groups of greedy claimants.
Ladar sites are complexes in EVE that come in a few variants. These sites are where the raw material for the creation of combat boosters originates. The first images shows a Ishtar class spaceship harvesting in the heart of a gas cloud.
The second image shown here is of a ladar site comprised of two gas clouds. Like most exploration complexes in EVE these sites can be defended in a variety of ways. This particular site is already in use by npcs and has a control tower there and other structures set up to utilise the gas clouds. When you start to mine the clouds an npc force undocks and defends their mining establishment. This npc force will require destruction if you want to take over this resource.
Another variant in 0.0 space comprises a site with 5 smaller gas clouds. These gas clouds are not defended by any npcs, but the gas clouds here are of a much more unstable type and during the process of mining them, they become more unstable and start to cause explosions which will damage any ships in the vicinity. Typical damage caused by a gas cloud is up to 1000 damage every minute.
Each of these two sites will yield 1000 units of material. A small cloud contains 200 units and a larger cloud yields 800 units.
One of the largest gas clouds site in 0.0 is calles a Gaseous Nebula, shown in the third image. This site comprises one large gas cloud which is heavily defended with ships and batteries, with new defenders arriving every few minutes to reinforce the area. Extreme caution is needed when attempting to do this site.
It is initially defended by 4 Siege Railgun batteries; 2 Guristas Stasis Webification batteries; 10 Battleship class; 8 Frigate class npcs. The amount of defenders can triple after a few minutes.
There is a further variant of Ladar Site which is a combat site called the H-PA Crew. This site has no gas clouds to harvest materials and is a combat site. This site requires the skill Hacking, as there are hacking containers, varying in number from 1 to 12, which can drop combat booster related items.
In order to be able to harvest gas in a cloud, you need to equip your ship with a gas cloud harvester. Each level of the Gas Cloud Harvesting skill allows an additional gas cloud harvester to be equipped upto a maximum of 5.
Like any other mining operation, harvesting the gas cloud material is best suited to one ship mining the resource and another to haul the material away. Though you may need a small fleet to clear the area first in some cases.