I believe the following in Jeff Cooper's original carry conditions - if I'm wrong someone will be along shortly to corret me
(yes I copied this from teh interwebs but it matches my memory and I was being too lazy to write it out myself). IIRC, this was developed re the traditional 1911. Some modern weapons, such as Glock/XD cannnot be in condition 2 and others, such as a Sig P-series with a de-cocker are designed to be carried in Condition 2 which is dangerous with a traditional 1911. What may be a dangerous condition for one particular firearm, may be the intended/desireable carry condition for another.
Conditions of firearm carry:
Condition 0. The chamber is loaded, the gun is cocked, and the safety is off.
Condition 1. The chamber is loaded, the gun is cocked, and the safety is on.
Condition 2. The chamber is loaded and the hammer is down
Condition 3. The chamber is empty and the magazine is loaded
Condition 4. The chamber is empty, the hammer is down, no magazine