Many novice players who have not yet grasped the meaning of a number of poker terms often ask the question of who is a poker grinder. This is the name given to a player who can play many hands over a certain period of time.
From the typical poker player, the grinder is distinguished by tremendous self-control, impressive composure, high physical and mental stamina.

The real masters of the game of poker

Thanks to the listed qualities, the grinder does not lose the freshness of reason, prudence and foresight, even if he spends a dozen hours in a row playing poker. Despite the fatigue, he will still play flawlessly and successfully. Such masters of the game are called good regulars, since they traditionally do not make mistakes due to nervousness, due to loss of attention and mental exhaustion.

The ability to always be in the black
This word has also become commonly used when applied to those players who are able to steadily follow the strategy of the least risks, which does not allow prolonged downstreams. The main goal of good regulars is simple and ingenious - to win as often as possible so that poker brings a steady income.
Developing anti-risk skills, dedication and patience allows grinders to achieve impressive financial heights. However, at the same time, their game looks boring and monotonous from the side. These undoubted disadvantages do not bother grinders at all, since they play poker not for the sake of fleeting pleasure and other thrills, but for the sake of solid continuous replenishment of their personal bankroll, that is, the game balance.

What are grinders like?
Grinders are divided into two major subclasses: live and online.
For fruitful grindering at real tables, you need to cultivate unshakable self-discipline and marathon endurance. Poker players of this type are forced to spend more time in the casino in one visit than even the dealers themselves, who, by the way, constantly replace each other, thereby allowing colleagues to relax.
A seasoned grinder is easy to identify by the fact that he does not take meaningless risks, does not give in to emotions and purposefully chooses less experienced poker players as opponents. His actions are motivated solely by the desire to win money, albeit not large ones.
Playing a huge number of matches in one evening, the grinder makes a big sum of money like a wholesale trader who sells every piece of product at a minimal mark-up. The ability to control nerves and feelings is rewarded with an impressive increase in bankroll, if the grinder manages to deftly play on the mistakes of opponents.

Source: https://www.lcarscom.net/what-is-a-grinder-in-poker/