Political Party:

A political organization that seeks to influence policy, typically by getting candidates and members to be elected for office

Party Systems:

Patterns of party politics characterised by the number of relevant parties in a country

Interest Groups:

Organizations that make demands in the political system on behalf of their constituents and members

Civil Society:

The set of organization in civic life outside the state through which citizens associate and articulate and advance their interests; includes civic associations, interest groups, and volunteer organizations

Interest aggregation:

The process by which political actors express their demands , needs, or wants in a political system, often through political parties and the party system

Elite parties:

Political parties in which membership and scope were largely restricted to a small number of political elites

Mass parties:

Parties consisting of large numbers of citizens as members and that undertake massive political mobilization

Catch-all parties:

Political parties that are flexible on their ideological positions and aim to attract support from a broad range of interest groups and voters

Dominant-party system:

Party system in which a country contains only one large political party that predominates politically, often controlling the legislative and executive branches of government

Single-party system:

An authoritarian system in which parties besides the single dominant party are banned or disallowed

Two-party system:

A political party system consisting of two significant parties that have a duopoly on opportunities to govern

Multiparty system:

A political party system consisting of more than two significant parties that have opportunities to govern

Fragmentation (of party system):

Contrasting with concentration, the extent to which political power and representation in a party system are characterised by relatively large numbers of relatively small parties