Alignment has the value of judging your standing with other players in darkfall online. You gain a alignment by killing a evil one, while losing a alignment by killing good one. The player in red is referred to as evil one, while someone in blue is considered to be in good standing with the members of his own faction. The value of gaining alignment is not equal to the value of losing alignment in terms of the efforts you paid. Killing only one in blue will turn you in red, while you should kill several ones in red helps you regain alignment.
There is an exception that you kill your own fellow will not make you lose your alignment. player clans have full diplomatic control over their relationship with other player clans, can declare war on other clans unilaterally. Clans being at war with each other can kill each other freely without losing a alignment penalty.