A teammate is a fellow member of a team. Because most teams are put together for the long term and travel together, teammates will develop strong bonds with one another due to the amount of time they spend with one another both on the field and outside it. If these bonds are positive, a team is said to benefit from good chemistry, and players who have a reputation of being good teammates will tend to be strongly valued, especially among substitutes. On the other hand, teammates who do not get along or who have a reputation as troublemakers will tend to move around a lot and not to be given as many opportunities to pursue their career even if they are otherwise productive players.
Many authors have written joint biographies of players who have spent a lot of time together as teammates. Researchers have looked at the issue of teammates from the point of view of degree of separation and discovered that no two major league players from the 1930s to the present (mid-2010s), no matter how obscure, are separated from each other by more than seven steps.