Box. Summary of definitions and types of interest groups.

Definitions
Pressure groups	Interest groups that contact decisionmakers of the government to influence policy-making processes in their favor. This term usually applies to sectional groups (which represent the self-interest of an economic or social group and whose members are restricted to them).
Special interest groups	Highly organized interest groups, usually with disproportionate economic (and, consequently, political) power over other organizations.
Types
Primary	Interest groups whose fundamental purpose is to engage in lobbying activities.
Secondary	Interest groups whose fundamental purpose is not political, but which can act in such a manner if necessary.
Institutional	They comprise public or private institutions (including individual companies).
Organizational	They comprise trade associations representing their members.