Explain the major functions of American parties.

What will be an ideal response?

The ideal answer should include:
1. A political party is an organization that runs candidates for public office under the party's name.
2. Parties contest elections, organizing voters in order to compete with other parties for elected offices. That entails recruiting people, organizing campaigns, fundraising, etc.
3. Parties organize public opinion, giving the public a limited channel of communication to express how they think government should operate. At the very least, voters can approve of the party that has been holding office by voting for it, or they can disapprove by voting for the opposition.
4. Parties engage in coalition building. They put together, or aggregate, various interests. They help overcome collective action and coordination problems.
5. Parties adopt policy changes proposed by smaller political groups. If third parties or political movements show that they have considerable support, their programs are often incorporated, though usually in more moderate form, by one of the major parties.