The existence of groups is prominently present in all civilizations. People spend their entire lives joining groups, taking part in them, and getting out of them. To understand why being part of a group is such an important characteristic of humans, we need to know what a group is and what group dynamics are. 

What are groups?

How do we define groups?

A group is basically a collection of human beings. More specifically, a group is defined as two or more individuals who are connected by and within social relationships. The connection does not need to be interpersonal. For example, the relations within groups based on ethnicity or gender are more psychological in nature. 

What types of groups exist?

The incredible large amount of groups that exists can be roughly devided into four types:

• Primary groups: people in primary groups tend to be really close. They interact a lot and influence the behavior of group members. Commitment and values are important. Becoming part of a primary group can happen involuntarily, like with families, or by choice, like with close friends. Usually, these groups persist for a long time. 
• Social groups: social groups tend to be larger and more formally organized than primary groups. Emotional involvement is lower and membership is less enduring. Work groups and clubs are good examples. 
• Collectives: collectives arise when individuals have something in common that draws them together, usually unintentionally. Interaction tends te be limited and once the experience or action ends, the group is dissolved. Crowds or audiences watching the same performance and queues are good examples of collectives.   
• Categories: individuals can be similar in some social way or they have a feature in common (e.g. citizens of Amsterdam). When members are part of a social category, they share a social identity. This means that knowing the ins and outs of the group contributes to one's self-concept. When outsiders start to categorise people based on group characteristics, stereotypes result. Social categories tend to create a sense of "we" and "us" versus "they" and "them".

Relationships and groups contribute to people's social capital which is defined as one's richness in terms of interpersonal relations. 

What are typical group characteristics?

Each group is unique in some way. However, the following characteristics are common to all groups:

• Composition: the individuals belonging to a group simply form the composition of that group. However, it should not be overlooked that groups can be more than the sum of their parts.
• Boundaries: boundaries describe the separation between members of a group and outsiders. A distinction can be made between open groups, where everyone is free to join, and closed groups, where people need to be accepted (for example, by voting) to be part of the group. Closed groups tend to be closer collectives where members identify themselves more with the group.
• Size: group size is an important determinant of other group features. The larger the group, the more likely it is that subgroups arise and the less likely it is that each individual has a close relationship with every other member of the group. A larger group requires more social ties to establish the same level of interconnectedness between its group members. People's capacity to maintain social relationships is limited, so connections become more indirect the larger the group is. 
• Interaction: interaction focuses on what group members actually do. For example, people talk, get into arguments an help each other. A distinction can be made between task interaction, describing a narrow focus on the group's tasks and goals, and relationship interaction (also called socioemotional interaction), describing emotional and interpersonal interactions that either sustain or undermine actions within the group. 
• Interdependence: when group member's actions, thoughts, feelings and experiences are influenced by each other, they are said to be mutually dependent on each other. Such interdependence can be symmetric with reciprocity (equal members), hierarchical without reciprocity (top-down), hierarchical with reciprocity (either equal or unequal) and sequential without reciprocity (A influences B and B influences C). 
• Structure: the group structure displays how a group is organized. Common aspects that are used for structuring groups are roles (e.g. leader and follower) and norms. Where roles describe socially expected behaviors, norms implicitly describe what behaviors should or should not be performed. 
• Goals: groups tend to have a purpose for their existence. Different approaches exist that classify group tasks. McGrath's task circumplex model distincts eight goal-related activities: generating planning and creativity tasks, choosing intellective and decision-making tasks, negotiating cognitive conflict tasks and mixed-motive tasks, and executing competitive tasks and performances. 
• Origin: groups can arise in different ways. Planned groups are deliberately formed whereas emerging groups are not explicitly organized. Adding another distinction, the one between groups originating from internal forces and groups that originate from external forces, gives the following four groups: concocted groups (individuals brought together; e.g. a military squad), founded groups (like a study group), circumstantial groups (like a group travel), and self-organizing groups (like waiting for the bus). 
• Unity: for groups to exist over time, group cohesion is needed. Group cohesion represents the solidarity of individuals that group together, often based on commitment to group goals rather than on social bonds. 
• Entitativity: whether the group indeed looks like a group. Entitativity is the perceived groupiness of a group. Interaction, emotional displays, similarity and coordination are all indicators of groupiness. Primary groups and social groups have higher entitativity ratings than categories and collectives. The Thomas Theorem predicts that if people define a group as real, it becomes real in its consequences. This is accompanied by expectations about these group members. This comes from a sense of essentialism or the belief that there are certain characteristics that distinguish the group members from others. 

An interesting phenomenon is that of social networks. Social networks are very group-like but because there are no clear boundaries that define who belongs to the social networks and who doesn't, they are not really considered to be groups. One can distinct joining a network (which can be achieved by establishing a single relationship with someone already part of a network) from joining a group. 

What are group dynamics?

What types of dynamic group processes exist?

Groups continually face interpersonal processes that occur between members of the group and with other groups. This has an impact on the group's nature, direction, actions and achievements. These influential processes over time are called group dynamics. Five such processes will be examined:

• Formative processes: formative processes are about the personal and interpersonal processes that contribute to the formation of the group. Key words are inclusion, identity, formation, cohesion and development.
• Influence processes: influence processes are about how the group functions as a collective. Each individual's motives, inclinations and preferences are important. Key words are structure, information, influence and interaction. 
• Performance processes: performance processes help facilitate and contribute to the group's performance. Combined skills are often necessary and teams (teamwork) and decision making are important key words. 
• Conflict processes: all groups experience tensions that can weaken or strengthen the group in the end. Additional key words are competition, resource distribution, power, uncertainty, harmony and cooperation. 
• Contextual processes: contextual processes are mainly about the group's location. Key words describing contextual processes are social and physical environment, growth, and change. 

How do group processes develop over time? 

Educational psychologist Bruce Tuckman differentiated the following five stages of group development which are closely linked to the processes from the previous paragraph:

• Orientation (forming): group members get to know each other and become oriented toward other members. 
• Conflict (storming): conflicts arise as group members find their place in the group. 
• Structure (norming): standards emerge and the resulting structure helps resolving conflicts. 
• Performance (performing): the group can focus on the work to be done.
• Dissolution (adjourning): group members withdraw and the group ceases to exist. 

Why is it relevant to study the nature of groups and their dynamics?

How do we understand people?

People have the tendency to review a person's actions based on individual qualities, even when the context is external or situational. This is called the fundamental attribution error (FAE). However, to explain an individual's behavior, we must understand groups. This comes from the notion that people show different behavior when they are alone compared to when they are part of a group. They aquire specific skills and most of their identity, attitudes and values during group processes. And more influential, people conform to group pressure. 

How do we understand the social world?

Studying groups is not only relevant for understanding people, it helps to understand organizations, communities and society at large. Individuals and society can be linked directly, but groups are an important connection between these two. Groups tend to influence cultural and institutional behaviors. One notable study conducted by Hofstede describes four key dimensions of variation in national cultures, being power distance, individualism, masculinity, and uncertainty avoidance. 

How does studying groups apply to practice?

Studying groups is especially important for decision making. Outcomes and actions are often based on decisions made in groups. For example, companies are led by executive teams and a medical team usually involves several doctors and nurses. People barely make decisions without help of other group members. This pragmatic orientation makes group dynamics such an interdisciplinary field of study. 

What is the significance of groups?

Some have tried to argue that people are better off without groups. They result in conclict, people start to behave differently in groups and many bad historical decisions have been made in groups. However, the value of groups is not ambiguous. Conflicts can be resolved and more importantly, groups contribute to one's values, norms, beliefs and identity. Being part of a group opens so many possibilities that it is important to understand how groups work. Learning how to relate with group members more effectively will enrich the group as well as the individuals in it.