A precinct, or district, is division of a town or city is usually for purposes of voting.
Delegates are usually elected by the voters of a district. Democratic voters choose Democratic delegates, and Republican voters choose Republican delegates.
Delegates can act as a go-between for the voters and the political party to which they belong. The delegates help with voter registration and take voter issues and questions back to party leaders.
Elected delegates generally act as campaign leaders for their party in their various districts.
After being elected a delegate, those chosen statewide then commonly elect other delegates to attend a state convention. This convention votes on such matters as new state party officers.
Those interested in becoming a delegate in their district should probably have an interest in politics. Involvement in local political issues can be very helpful.