The main difference between the contio and other public assemblies in Rome, such as the comitia, is that the citizens who attended contiones were there to hear speeches and not to vote.
The contio merely served a communicative function, offering magistrates the opportunity to give the people a report of what had been decided during a senate meeting or to discuss a proposed legislative bill (rogatio) in front of the citizens to help them make up their mind before they had to vote on it in other assemblies.
The practice of holding contiones is said to have started under the Roman monarchy, where the king (rex) was the only one who could summon a contio as well as the sole person who had the right to speak at this assembly.
Every magistrate, as well as tribunes of the people, got the right to call a contio and address the crowd, or invite others to give a speech on a topic of the convener's choice.
According to this theory, these shopkeepers were joined by other lower-class Romans who sought to escape their narrow housing conditions by hanging out in public places such as the forum.
Moreover, these higher-class Romans would have had the education that was needed to appreciate and understand the argumentation the magistrates used in their speeches, which sometimes included complicated references to history or law.
Many contional speeches have been lost over time or have never been recorded in the first place, likely because the topics with which they dealt were not significant enough or because the speaker did not use interesting or engaging rhetorical strategies.
[25] Judging from the ancient source material described above, speeches delivered at the contio seem to have shared several rhetorical and argumentative characteristics.
The rules for summoning contiones of this kind were similar to those for the political assembly: under the monarchy only the king (rex) had the right to do so; during the republic every magistrate[dubious – discuss] received this right.
Military contiones shared the communicative character of their political counterparts: they did not serve to cast votes or make decisions.