Definition of bubble
The bubble in poker is only present in tournaments (or sit'n'gos). The bubble is the phenomenon that occurs just before the paid seats. For example, in a tournament, 1000 players register. This tournament offers 100 paid seats in a predetermined structure. The first paid seat (the 100th position) will pay about 150% of its entry fee. So, if the tournament had a buy-in of €100, finishing 100th would give you about €150. Finishing 101st would get you 0. ? with say 110 players left in the tournament, there will be a bubble phenomenon where the majority of players will be more cautious and conservative in getting into the paid seats. In short, the bubble is the time just before the paid seats. When this stage is over, the bubble is said to be burst.
The philosophy of the bubble
There will generally be 2 philosophies of the bubble, therefore, 2 types of players with 2 different visions. The first type of player, more aggressive, will say that since the approach of the paid seats (the bubble), the players are more conservative, he will be more aggressive and bluffing to take advantage of this passivity. He is the one who will play for everything. And there is the 2nd type of player who will be more conservative and take as little risk as possible to reach the paid seats.