All-in is a poker term that you’ll hear quite often at the tables, especially in tournaments. In short, it describes an action by which a player is betting all chips they have in their stack.
When announced verbally, “all in” is binding, meaning that if you say these words while involved in a hand, you are letting the table know you are betting all of your chips, so be very careful using these two words as a joke. In most poker games, verbal declarations are binding.
For example, if you bet $25 and a player with $100 in front of them announces all-in, they are effectively raising your bet to $100. If no other players are involved in a hand, an all-in also means the end of betting action, even if you have more chips behind.
Verbally declaring that you’re all in can be quite useful in tournaments when you have a lot of chips in front of you, and it is hard to push all of them at once. By using the verbal declarations, you’ll avoid any confusion and make your intentions clear.