The Hiding rule represents warriors concealing themselves in a way that our unmoving and dramatically posed models cannot. A hiding warrior keeps as still as possible, just peeking out of cover.
A model can hide if it ends its move behind a low wall, a column or in a similar position where it could reasonably conceal himself. The player must declare that the warrior is hiding and place a counter (such as a coin, dice, etc) beside the model for it to count as being hidden.
A model that runs, flees, is stunned or charges cannot hide that turn. His sudden burst of speed prevents it.
A model may stay hidden over several turns, so long as he stays behind a wall or similar feature. He may even move around provided that he stays hidden while doing so. If an enemy moves so that he can see the hidden warrior, the model is no longer hidden and the counter is removed.
When hidden, a warrior cannot be seen, shot at or charged. When hiding, a model cannot shoot or cast spells without giving away its position. If a hidden model shoots, or moves so that he can be seen, he is no longer hidden and can be shot at.
A model may not hide if he is too close to an enemy model - he will be seen or heard no matter how well concealed. Enemy warriors will always see, hear or otherwise detect hidden foes within their Initiative value in inches. So a warrior whose Initiative value is 3 will automatically spot all hidden enemies within 3".