The question "What is a casino deposit bonus?" usually comes up after a bonus has vanished, taking its winnings with it. The cause is almost always a condition in the terms: a deadline that passed, a withdrawal made too early, a cap on winnings or a clause about irregular play. Each of these can be seen in advance, and a few minutes with the terms show which of them apply to a given offer.
Casinos can change their bonus terms, and most promise that a bonus already claimed stays under the version accepted at the time. The promise matters only if the version can be shown, so saving the terms on the day an offer is taken is worth the minute it costs. The same goes for anything support agrees in chat: a saved copy of the conversation settles more disputes than a memory of it.
Requesting a withdrawal while a bonus is active often cancels the bonus and everything won with it, and some casinos apply the rule even to cash deposited alongside it. A player can usually cancel a bonus on purpose from the account page, which frees the cash balance at the cost of the bonus. Knowing where that option sits, and what it removes, turns an accidental forfeit into a choice made knowingly.
Usually not. Opening more than one account per person or household is a common abuse clause, and it can void the bonus and its winnings.
Often yes. Asking to withdraw while a bonus is active can remove the bonus and its winnings, and some casinos apply this to the deposited cash too.
A saved copy proves which version of the terms applied on the day the offer was taken, which matters if the casino later changes them.
Typical examples include betting both sides of an even money bet, switching to low risk play to clear wagering, or sharply raising stakes after conversion.
Usually from the account page. Doing so frees the cash balance but removes the bonus and whatever was won with it.