Conditions are various status effects one can gain during gameplay.
Bleed
A Bleeding entity will take a certain amount of damage per turn until they stanch it. Blood makes your presence more noticable, as some creatures may smell blood easily, or a blood trail is left behind you.
Daze
The entity is unable to act normally. A Dazed creature can take no actions, but has no penalty to AC. They usually respond with bewilderment, confusion, irrational anger at certain things or people, or nothing at all.
Deafened
Deafened entities take a penalty to their Perception Skillchecks based on audio, Initiative, and AC. The penalty depends on the severity of the Deafening.
Fatigued
A Fatigued entity moves at half speed, and takes a penalty to Strength and Dexterity Skillchecks. Fatigue can easily be ailed by a little rest, or an attempted Health Skillcheck.
Fright
A Frightened entity flees from the source of its fear as best it can, as well as taking a penalty on Attack Rolls. A Frightened creature can use special abilities, including spells, to flee.
Grappled
A Grappled entity is restrained by another entity, trap, etc. Grappled entities cannot move and take a hard penalty to Dexterity Skillchecks, as well as Attack Rolls. One may break free from a Grapple with a high enough Strength or Dexterity Skillcheck.
Invisible
Invisible entities are visually undetectable. An Invisible creature gains a bonus on Attack Rolls against opponents that can't detect their presence, and ignores the opponents Dexterity bonuses to AC. A high enough Intuition or Perception check can be made to detect an Invisible entity.
Nausea
Nauseated entities experience stomach distress and are unable to Attack, cast Spells, concentrate, or do anything else requiring strict attention. If severe enough, Naueseation may lead to vomiting or other bodily responses.
Paralyzed
A Paralyzed entity is frozen in place and unable to move or act. A Paralyzed entity has Dexterity and Strength scores of 0 and is helpless, but still conscious mentally.
Prone
The entity is lying on the ground. A prone defender gains a +4 bonus AC against ranged attacks, but takes a –4 penalty AC against melee attacks. They may take a penalty when taking Attack Rolls as well.
Unconscious
Knocked out and completely helpless, Unconsciousness can result from having negative HP, or from excessive nonlethal damage.
Poisoned
A poisoned entity may develop an Illness if the sickness isn't treated in a timely manner, or lead to full blown Nausea.
Burning
A Burning entity will take a certain amount of damage per turn until their fire is put out. The entity may also put out his Burning by remaining prone for 3 rounds.