- Various references to High Security, Low Security, Null Security, and Wormhole Space redirect here. For the EVE University Campuses focused on student activities in each of these areas, see Hi_Sec_Campus, Low-Sec Campus, Nullsec Campus, or Wormhole Campus, respectively. Other campuses are listed at Campuses.
A star system's Security Level is a rough measure of how hazardous that particular system is. Players also commonly use the terms Sec Level, System Sec, Security Rating, and Sec Rating. It is displayed in-game as a positive number with a single decimal place in the range 1.0 to 0.0. Security level should not be confused with Security Status, which is an attribute attached to a player character.
The security level of a player's current system is always displayed in the System Information display on the upper left of the screen, both in space and while docked.
There are three general classifications of systems based upon system security: High Security, Low Security, and Null Security.
Empire space is the name given to the regions which the four main NPC factions hold sovereignty (High Security and Low Security). In Empire space, whether high or low security, stealth bombers can't use bombs and players cannot deploy bubbles.
High Security systems are those with a security level of 0.5 to 1.0. CONCORD will react to hostile actions between pilots, with the response time ranging from almost instant in 1.0 space to up to 10 seconds in 0.5 space. Players also commonly use the terms High-sec, Highsec, Hi-sec, and Hisec.
In these systems, stargates may be patrolled by NPC CONCORD, customs, and/or faction navy ships, and stargates and stations will have sentry guns. Aggression (i.e. committing a Criminal-level offense) will provoke a response from CONCORD and any nearby sentry guns. Aggression resulting in the destruction of another player's ship and/or pod will result in a loss of security status.
Regions which are primarily HiSec:
- The Citadel
- The Forge
- Sinq Laison
- Verge Vendor
Low Security systems are those with a security level of 0.1 to 0.4. Players also commonly use the terms Low-sec, Lo-sec, Lowsec, and Losec.
In these systems, stargates and stations will have sentry guns (although fewer than in Highsec), but CONCORD will not react to hostile actions between pilots, although any nearby sentry guns will still open fire on the attacking player(s) and unprovoked attacks will cause losses of security status.
Regions which are primarily LoSec:
- Black Rise
- The Bleak Lands
- Molden Heath
- Solitude (with a HiSec island, that includes Project Solitude)
Null Security systems are those with a security level of 0.0. Players also commonly use the terms Null-sec, Nullsec, and 0.0 (pronounced "zero zero", "zero dot zero", or "oh dot oh").
These systems are essentially lawless and no NPC organizations will respond to aggression, nor will actions of any kind result in a loss of security status. In nullsec the gloves are off: stealth bombers can use bombs and players can deploy bubbles; players frequently fly under not-blue-shoot-it ('NBSI') rules of engagement (see also: EVE University Rules of Engagement).
NPC NullSec is null-security space where the sovereignty is claimed by NPC factions, similar to normal 'Empire' space, and therefore cannot be claimed by capsuleer alliances.
Regions classified as NPC NullSec:
- Curse, claimed by Angel Cartel
- Great Wildlands, claimed by Thukker Tribe
- Outer Ring, claimed by Outer Ring Excavations
- Stain, claimed by Sansha's Nation
- Syndicate, claimed by Intaki Syndicate
- Venal, claimed by Guristas Pirates
University pilots are allowed to enter all of these, for purposes including PvP and PvE (see also: EVE University Rules).
- Main article: Sovereignty
In the rest of nullsec sovereignty is claimed (or contested!) by capsuleer alliances. Any stations in claimable nullsec will be player-owned and will usually only allow their owners' allies to dock.
EVE University members are allowed to enter Claimable Nullsec space to PvE and PvP, but may not get engaged in structure or sovereignity battles (see: EVE University Rules).
|A long, long time ago...|
|University policy, until March 2014, was that University pilots were not allowed to enter claimable nullsec, unless in a fleet lead by an ILN Officer, in order to preserve the University's neurality. That changed in March 2014, after a successful 1-month experiment, and Azmodeus Valar mailed out "[O]ur month long test of increased Sov Null access has been a success. We will be continuing it indefinitely. This means that anyone can lead a fleet into sovereign null security space for PvP purposes. Do not engage in PvE activities in Sov Null space, and do not participate in structure or sovereignty battles." See this forum thread for more details. This was later updated to allow PvE activities as well, see the Rules of Engagement page on claimable nullsec.|
A regularly-updated map of player-owned territory is available here.
Regions classified as Claimable NullSec:
- Cloud Ring
- Cobalt Edge (also a Drone Region)
- Delve (some systems: The Blood Raider Covenant)
- Etherium Reach (also a Drone Region)
- Fountain (some systems: Serpentis)
- Geminate (some systems: The Society of Conscious Thought)
- Malpais (also a Drone Region)
- Outer Passage (also a Drone Region)
- Paragon Soul
- Period Basis
- Perrigen Falls (also a Drone Region)
- Pure Blind (some systems: Mordu's Legion, Sisters of Eve)
- Scalding Pass
- The Kalevala Expanse (also a Drone Region)
- The Spire (also a Drone Region)
- Vale of the Silent
- Wicked Creek
- Main article: Wormhole Space
In terms of security mechanics, Wormhole Space ("w-space") is similar to nullsec: CONCORD does not monitor what happens in wormhole pockets, and players can use bombs and bubbles at will.
W-space also functions differently from known space ("k-space") in that players do not appear in the Local chat channel until they speak in it. This means there could be 1 player or 100 players in a wormhole system and you would not be able to tell the difference just by looking at the local window.
EVE University pilots are welcome to enter Wormhole space, but should be aware of its dangerous nature, and may not perform PvE activities in wormholes controlled by allies of the University (see also: EVE University Rules). The University maintains a Wormhole Campus to teach its students how to survive and thrive in wormhole space.
Game Mechanics affected by System Security
Various game mechanics are affected or limited by system security. These include:
- Asteroid types found in asteroid belts. More lucrative asteroids are generally found in lower-security systems.
- General difficulty of rat spawns, including belt and gate rats. More difficult rats are generally found in lower-security systems.
- General difficulty of cosmic anomalies and cosmic signatures. More difficult sites are generally found in lower-security systems.
- Reward level of missions. Greater rewards for the same mission are given by agents in lower-security systems.
- True capital ships (i.e. ships that specifically require the Capital Ships skill) may not enter highsec systems.
- Specific types of wormholes will only form in specific classes of space.
Differences going from High to Low Sec
- True capital and supercapital ships may now use stargates
- CONCORD no longer responds, however NPC guns on gates and stations will respond to illegal aggression
- Moons have extractable materials
- Player Owned Starbases do not require Empire Charters to operate
Differences going from Low to Null Sec
- Player alliances may hold sovereignty in solar systems
- Security status does not change from PVP aggression
- Items flagged with the Banned in Empire Space attribute can now be used, including launching bombs, anchoring bubbles, and firing doomsdays
- Sentry guns are no longer present around stargates and NPC stations
Differences from Null to W-space
- Local chat does not display all capsuleers currently in the system, only those that have recently spoken in Local
- Frequent and heavy use of the Directional Scanner is recommended
- No stargates are present, wormholes are the sole means of travel
- As truesec -1.0, w-space has the highest concentrations of planetary resources
- Moons have no extractable materials
- Aggression timers do not restrict jumping through wormholes as they do stargates and docking
- Cynosural fields cannot create links to other systems
The security level of a system may limit what may be anchored in that system. 
- 0.9 - 1.0: Containers may NOT be anchored. Starbases and starbase structures may be anchored except for moon mining structures, and structures requiring anchoring corp to have system sov.
- 0.5 - 0.8: Containers, starbases and starbase structures may be anchored (above restrictions still apply)
- 0.0 - 0.4: All containers and starbase structures may be anchored, except structures requiring anchoring corp to have system sov. 
- -1.0 - 0.0: All containers and starbase structures may be anchored, assuming that anchoring corp has system sov. Player-built stations may be constructed in systems where the corp building the station has sov (as of this writing, player-built stations are completely indestructible and are limited to one station per system).
If a player with a a sufficiently low security status (below -2.0) enters a high-sec system, they may be attacked by NPC faction navy ships.
A given system's security level is actually a real number between -1.0 and 1.0 (this is known as the system's True Security Level, True-Sec, or Truesec). It is modified and rounded and displayed as the system's security level according to the following rules: 
- -1.0 to 0.0 = nullsec
- 0.0 to 0.05 = rounded up to lowsec (0.1 security level)
- 0.05 to 0.45 = rounded half up (lowsec)
- 0.45 to 1.0 = rounded half up (highsec)
For nullsec systems it may be useful to know a system's true security, as even though all nullsec systems are displayed as "0.0" in the game, they have true security ratings from -1.0 up to 0.0 - and this true security rating affects various game mechanics, such as asteroid belt and rat quality. A system's rounded truesec value is available via the in-game map, and the unrounded value can be found through the official datadump or any third-party utilities that use the datadump or the data extracted from it.
|A long, long time ago...|
| In the past, truesec values in the range (0.0, 0.5) were rounded half up, i.e. rounded down to 0.0 because all numbers in that range are below 0.5. This was a bug, because EVE considers all systems above a trusec rating of 0.0 to be lowsec but the game displayed their security level as "0.0". This bug not only caused some confusion (there were sentry guns within apparently nullsec systems) but also some problems in the form of inadvertent security status loss in what seemed like nullsec.
This bug was fixed in the Revelations expansion , and the game now uses the rules above. This ensures that any system displayed as "0.0" is truly nullsec. Some third-party utilities may not know of the above rules, and so may incorrectly identify some lowsec systems as nullsec.