Tuckman's stages of group development

Tuckman's stages of group development is a model of group development made by Bruce Tuckman in 1965. It has four phases: Forming, Storming, Norming and Performing. 
Tuckman believed that these stages are all necessary and always happen in order for a team:
This model has become the basis for later models.
More reading on this topic can be found here: