While sneaking your speed is halved as you try to move silently and unnoticed.

If you end your move behind or with Partial Cover or Full Cover you can try to Hide to become Hidden.

After each move you must be behind some kind of cover to remain [Hidden].

Each time you use a move type while Sneaking, you must roll your Sneak vs every Enemy (or opposing creature team) within a 20ft sphere of the path you moved. Each target only rolls once during the move.

Unless otherwise stated you must be behind cover after the move is completed to remain Hidden.