Blind

From HGWiki

Blindness is a status effect that leaves a target unable to see.

This effect causes a 50% miss chance and a -4 penalty to all attack rolls for the target, while giving those attacking the target a +2 bonus to attack rolls. A blind creature is considered flat-footed, and is unable to directly target distant creatures with spells or attacks. Additionally, there is a -4 penalty to Discipline, Hide, Move Silently, Open Lock, Parry, Pick Pocket, Set Trap, and Tumble.

True Seeing negates most of the effects of being blind, leaving only the 50% miss chance.

Similarly, Blind Fight negates some of the effects of being blind, leaving only the -4 penalty to attack rolls, the -4 penalty to skills, and the inability to target creatures at a distance.

The -4 penalty to attack rolls is for attacking an unseen character. It is not applied multiple times for other instances of not being able to see the target (e.g. if the target is invisible).