A standing hand in blackjack is a card total at which the player or the dealer stops taking cards. The term is used at land-based and online tables alike. If your strategy says to stand on a particular number, it means you stop asking for more cards once you reach it.
The reasoning is about risk: from that total, another card is more likely to bust you than to help, so standing gives you the better chance of winning the hand. Dealers have no choice in the matter, because house rules tell them exactly when to stand. A common rule is that the dealer stands on soft 17, a hand in which an ace counts as 11, such as ace-six. The dealer’s rules are not the same everywhere, though, so check them before you play.
Standing rules on online tables
Whether the dealer stands or hits on soft 17 changes the house edge, so it is one of the first rules informed players look for. Make sure every blackjack game in your lobby states its standing rule, deck count and payouts clearly in the help screen.