There are four major player types in poker and while most people will have more than four categories into which they place players, all of those categories can be placed into one of one of these four player types. The types are fish, rock, fox and maniac.
Fish are the vast majority of poker players. The main thing that identifies a fish is that they make the mistake of calling too much. There are multiple types of fish and herein lies the area in which most people will have more than just the fish category for their players. For example, they might classify one player at the table as a calling station because they are always trying to call and get lucky whereas they might classify another player at the table as someone that overvalues their large unpaired cards before the flop. A third player might make it into their repertoire as a player that draws too much. All three of these players are different within the specifics of the mistakes that they make, but in the end the overarching mistakes they make is still calling too much and for that reason all of them are fish.
Rocks are essentially the exact opposite of fish. They will not call enough. Rocks will only play the best hands before the flop and they will play hands passively unless they have a really strong hand in which case they will raise. Because of this behavior, rocks can eat fish alive at the lower limits of most poker games as they will be going to war with hands that are often 3 to 2 favorites or better against the fish. Over the long run, a rock-like strategy can make a lot of money at the lower limits, but rocks do not do that well at the upper limits because of the presence of foxes.
Speaking of foxes, they are the player type that you should aspire to be. Foxes are exceptionally good players that know how to read, know when to move and know how to minimize losses and maximize profits in the hands that they play. Poker professionals are foxes. There is not anything aside from the ability to win consistently at the best poker games in town that really defines a fox as there are multiple playing styles that a fox could be as long as they are good at manipulating the other players at the table into calling with worse hands and folding better ones. Foxes may appear to be rocks or fish at different stages of the game, but rest assured that foxes do not make that many mistakes. In modern terms, some people refer to foxes as sharks.
Maniacs are players that just blow chips into the pot time and time again. If you see a player doing this and consistently showing poor cards, they are most definitely