Some bacteriophages infect and immediately destroy their hosts in a burst of new viruses, while others can be stealthier, integrating their genome into the genome of the host and remaining there quietly even over multiple generations of the bacteria. When something stresses the host, such as DNA damage, these integrated phages (prophages) become active and start producing new viruses, killing their host like the other kind does.
In this study, one kind of bacteria release a chemical that wakes up phages in a competitor species of bacteria. This is helpful for competition, but even more interesting is that out of the six prophages in the competitor species, the chemical wakes up only one of them. Such selective phage induction could be interesting to study.