Betting limits apply to the amount a player may open or raise, and come in four common forms: no limit, pot limit (the two collectively called big bet poker), fixed limit, and spread limit. All such games have a minimum bet as well as the stated maximums, and also commonly a betting unit, which is the smallest denomination in which bets can be made. For example, it is common for games with $20 and $40 betting limits to have a minimum betting unit of $5, so that all bets must be in multiples ...
In a broader sense of the word, betting in poker can refer to any action where you’re placing chips forward into the pot. This definition applies it’s a bet, call, or raise. More commonly, though, it merely refers to a bet –. and where a player places forward an initial amount of chips to open up the action.
Any poker game can be played with a limit betting structure, however. A Limit Texas Hold'em game played at $2/$4 limits generally means the blinds are $1/$2. Limit games are played with a "small bet" and a "big bet", with the big blind usually equal to the small bet. Many limit games use a structure where the maximum raise is equal to the small bet in the early betting rounds and increases to the big bet amount in later betting rounds.
Allow me to give you a fundamental yet very awesome rule about good poker betting strategy: The size of your bets should always be made relative to the size of the pot. This just means that whenever you make a bet, you take into consideration the size of the pot and bet according to how big or small the pot is.
This means in the first round of betting, no one can “check,” that is, everyone has to bet. In poker, you have five actions available to you during a round of betting. Two actions are for when no one has put money in the pot in front of you, and three are for when you're facing a bet.
Poker is played with various betting structures and rules for how much you can bet, raise or check-raise. In some formats and games, for example, you can only bet a certain fixed amount for any bet and the amount of bets per round are capped; in other formats you can bet all your money in one go at any time.