Where "What is a wallet address?" is concerned, one rule covers most of it: every detail must line up before coins are sent. A coin deposit travels on a public network, and the casino only sees it once that network has confirmed the transfer. The coin, the network it runs on, the address and sometimes a memo all have to match what the deposit page shows. Most failed crypto payments come from a mismatch in a single one of those details, and very few can be undone after sending.
A transfer is credited after the network has confirmed it a set number of times, and the casino decides how many confirmations it waits for. On a fast network that takes seconds; on a busy or slower one it can take an hour or more. A deposit that shows as sent in the wallet but not yet in the account is usually still collecting confirmations, and the transaction hash lets anyone follow its progress on a public explorer.
Many coins exist on more than one network, and a casino usually accepts each coin on only one or two of them. The deposit page names the network next to the deposit address, and a wallet must send on exactly that network. Coins sent on a different network can arrive at an address the casino does not watch, and recovering them depends entirely on the goodwill and tools of its payment team, when recovery is possible at all.
Withdrawals run the same route in reverse: the player supplies an address, and the casino sends coins on the network it supports. An address from a wallet or exchange that does not support that network can lose the payment, so the receiving side deserves the same care as the sending one. A small test transfer before a large one costs one extra fee and confirms the whole route, including any tag the receiving account needs.
Further questions
What happens to coins sent below the minimum deposit?
Undersized deposits are often never credited, because processing them would cost the casino more than the coins are worth.
Is a small test transfer worth the extra fee?
Sending a small amount first costs one more fee but confirms the whole route, address and tag included, before a larger sum moves.
What should be checked before a crypto withdrawal?
Whether the receiving wallet or exchange supports the network the casino sends on, including any tag it requires, or the payment can be lost.
What is a memo or destination tag for?
Some networks need it to tell the casino which account the coins belong to; without it, the transfer waits for support to match it manually.