The Team Handbook*, says:
Teams go through four predictable stages of growth as they learn to work together effectively.
The key word in this is effectively.
Stage 1: Forming
When a team is first organized or when there is a change up in who is on the team or who leads the team, forming will be the best way to describe the team.
At this stage, team members are exploring the boundaries of acceptable group behavior and trying to establish their position and status with the team. While being somewhat excited about the opportunity to be on a team or reorganizing a team, they may be suspicious and anxious about how everything will work. It is perfectly normal at this stage to see little progress, as the team may complain about the purpose of the team and are inclined to get stuck in discussions that end up nowhere. Impatience and frustration are common symptoms of members on the team in this stage.
Stage 2: Storming
At this stage the team members are beginning to realize that the task and responsibilities of the team are different and more difficult than first imagined. Some may become impatient with the lack of progress and begin to vocalize their ideas and resist the need to collaborate. Others might simply withdraw as discussions may start to heat up. They are beginning to understand one another and realize how the differences in personalities, agendas and communication style are going to impact them. Storming takes on many different faces, but it is part of the predictable process of a team trying to work together. Sometimes a team stays in stuck in storming and has a low success rate.
Stage 3: Norming
This is the stage when team members are accepting the individuality of each person, beginning to trust the ground rules to keep equality in the process, and realizing that competitiveness must give way to cooperation. They begin to look forward to the contribution of the others on the team as a sense of team spirit and dedication to a common goal unfolds. With this shift in team energy, they begin to make significant progress.
Stage 4: Performing
Team members now have insights into personal and group processes. They recognize, and even anticipate, how they can each contribute to the mission. They quickly identify and resolve interpersonal communication problems. They develop a synergy that enables rapid progress.
* Scholtes, Peter R. and other contributors, The Team Handbook. Madison, WI: Joiner Associates, Inc. 1988