During the launch of an Apollo spacecraft by the Saturn V rocket, the flight could be aborted to rescue the crew if the rocket failed catastrophically. Depending on how far into the flight the crew were, they would use different procedures or modes for that. None of the abort modes ever had to be used.
Houston's announcements of the current abort mode and the spacecraft commander's acknowledgements belong to the few things being said on the radio link during the first minutes of flight.
If the rocket failed during the first phases of the flight, the Emergency Detection System (EDS) would automatically give the command to abort. The reason is that life-threatening situations can develop too fast for humans to discuss and react to. In the later, less violent phases of the ascent, the EDS was turned off and an abort would have to be initiated manually.
Of the five abort modes, the modes up to two (II) are variations of jettisoning the entire rocket followed by an immediate landing in the sea (splashdown). Mode three (III) and up are variations of jettisoning only the failing rocket stage, using the other stages to contine into Earth orbit. Once there, a backup Earth orbit mission could be performed so that the flight was not entirely in vain. In all cases, the Command Module (CM) with the astronauts performs a splashdown by
Apollo's planned-for abort modes were, in chronological order: