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 LP rewards for the same mission are given by agents in lower-security systems.
• Specific types of wormholes will only form in specific classes of space.
• In 0.5 space and below the moons can be mined with refineries.

• CONCORD destroys any criminal player.
• NPC navies will chase players with very low faction standing.
• Player with a a sufficiently low security status (below -2.0) may be attacked by NPC faction navy ships.
• True capital ships (i.e. ships that specifically require the Capital Ships skill) may not enter high security space.
• Cynosural fields cannot create beacons for jump drives.

• CONCORD no longer responds, however NPC guns on gates and stations will respond to illegal aggression.
• Player-Owned Starbases do not require Empire Charters to operate.

• PVP aggression does not change player security status.
• Items flagged with the Banned in Empire Space attribute can now be used, including launching bombs, anchoring bubbles, and firing doomsdays.
• Sentry guns do not take any actions towards players who aggress other players.

• 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.
• Aggression timers do not restrict jumping through wormholes as they do with 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 structures requiring anchoring corp to have system sov.
• 0.5 - 0.8: Containers, starbases and starbase structures may be anchored except for structures requiring anchoring corp to have system sov.
• 0.0 - 0.4: All containers and starbase structures may be anchored, except structures requiring anchoring corp to have system sov. [2]
• -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).

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 rounded and displayed as the system's security level according to the following rules.

• If the true security is in between 0.0 and 0.05 the security is rounded up to precision.
• Otherwise round to precision.

Many security related mechanics use the true security instead of the rounded security status. For example belt rats and mission rewards.

The true security is not visible anywhere in game, instead it can be found in the official datadump or from ESI API. Many third party mapping tools such as Dotlan also show the true security.