The Republican Party Convention is similar to the Democratic Party Convention, at both next presidential candidates are nominated. The candidates have to be chosen by the party members with a complete consensus.
The convention is convened by the Republican National Committee under the rule 13 of the party constitution. The convention signifies end of the presidential primary season and start of general elections campaign.
The sole purpose of the convention is the nomination of the next presidential candidate, although it also discusses the agenda and rules for the election campaign of the party and assigning of responsibilities to party members.
In the recent years, generally next presidential candidate is tipped well before the convention is held, while the convention itself has become a formality or an occasion to announce the candidate officially and formally.
The party delegates from all the states of the country are invited at the convention since their input is essential to nomination of the candidate. It is true that by the convention almost all party members know who is going to be the next presidential candidate.
The convention is addressed by the party members, especially by the president, if the current president is elected from the party. For example, in case of re-election of the same candidate, the party's candidate is the same person. The president then addresses the convention and sets out main agenda of the part in the next general election.
At the convention, party members from different states can raise issues of their concerns and discuss them. The convention thus stands out to last consultative meeting with the party members and then general election campaign is started formally.