The Festival is an upload civilisation, originally intended to repair galactic information networks, that travels from system to system via starwisps, building the facilities it needs from local materials when it arrives. It usually prefers to interact with other upload civilisations, but any will do in a pinch. It asks for information it is unfamiliar with from those it visits, and will make any kind of payment in exchange.
No individual member of the Festival makes an appearance in the novel. Traveling in the Festival's vast spare mindspace are a number of other upload species that are separate from them but part of every visit.
- The Bouncers: The Festival's brute-force defence, used when "a big stick and a smile were all that was needed." During the novel three automated Bouncer ships take on the Lord Vanek and the rest of the New Republic's naval fleet; one of them is destroyed but the Bouncers' self-replicating robots eat all the opposing ships.
- The Critics: A matriarchal culture that instantiates their physical bodies, which resemble large mole-rats, upon arrival at a new system. Despite their appearance, they are descended from humans and share similar brains. They pay for their passage by providing high-level commentary and analysis of the visited civilisation. During Singularity Sky, one of them, Sister of Stratagems the Seventh, leaves their orbital perch and goes to the planet's surface to better assess whether the Rochardians are truly sapient.
- The Fringe: A subgroup of the Festival that uses the planet as a medium for art. Their projects range from the introduction of extraplanetary flora by the Flower Show to inducing solar flares to create aurora displays. They are considered potentially the Festival's most dangerous element, although this is more from their recklessness than design.
- The Mimes: An offshoot of the Fringe that in the past suffered bit rot from a solar flare and has become corrupted. On a visited planet, the Mimes turn those they encounter into cyborg zombies that attempt to do likewise to others they encounter. It may have been a misguided attempt to communicate.
(From Wikipedia about the book)