Also known as CHM. In FIFA Ultimate Team, the chemistry is a factor that defines the compatibility of a player in his current position with his preferred position, his squad's formation, the relation with his teammates in other positions and the team manager. These individual factors are called Player Chemistry and the overall Player Chemistry of a team will build the Team Chemistry.
Putting players in their preferred positions and linking them with teammates from the same Club or League will produce better Player & Team Chemistry. You can also build chemistry by pairing players who have the same nationality or enlisting a manager with the same nationality as players on the roster.
The Player Chemistry is visible in the Active Squad as connecting lines between players and chemistry nodes and its quality level is represented in colours, where the red is low, the yellow/orange is medium and the green is high. The better chemistry results the better effects on the pitch. The Team Chemistry is also visible on Active Squad page as rating bar in Overall Squad menu.
The effects of Chemistry are applied to players at the start of the game. These effects are governed by a combination of Team Chemistry and Individual Player Chemistry. A player in the starting XI gets 25% of effects from Team Chemistry & 75% from Individual Player Chemistry. A player who comes on as a substitute gets 25% from Team Chemistry & 75% from Static Individual Player Chemistry of 5.