The common troll is nocturnal. Their natural tendency to spend daylight hours dormant led to the stories of them turning to stone when hit by the sun. Though apparently unintelligent, this is due to heat negatively affecting the conductivity of their silicon brains, which operate in a similar fashion to computer circuits (in essence a trollish form of hyperthermia). In the coldness of the high mountain areas that they usually call home, they can, in certain respects, be quite clever. When sufficiently deep-frozen, they can perform exceptional mathematical feats, possibly involving quantum computing. Oddly, the silicon-based trolls are capable of freezing to death if exposed to sufficiently cold temperatures, although the book Men At Arms makes it clear that such temperatures are far lower than fleshly creatures, such as dwarfs, could survive.
Rock and stone is also the natural diet of trolls, and they have diamond teeth to enable this. Quartz is held to be unhealthy, as it "clogs the arteries", and ammonites are also avoided as a sign of the rock having gone stale. Trolls frequently use the word coprolite where a human would refer to fresher fecal matter; this may have a physiological analogue. They can gain some nutrition from the mineral content of carbon-based animals (including humans, although they never do that any more, honest), but not much.
Trolls often drink molten minerals for recreation. Due to the heat affecting their brains, this has the much same effect on them as alcohol does on humans. Electrolyte solutions have a similar effect, presumably more directly. One such drink is the Electrick Floorbanger (a reference to the Harvey Wallbanger drink). Troll "beer" is ammonium sulfide dissolved in alcohol.
"Slab" (a street name for ammonium chloride mixed with radium) has a similar effect to electrolyte drinks, but much more severely. It eventually melts the troll's brain. The clean version generally makes a troll sit in a corner to watch the colours, but variants exist with more disturbing effects ("disturbing" for either the troll, anyone nearby, or both).
Trolls are theoretically immortal, but as they get older they get bigger and slower and tend to be more inclined to sit and think. They call this "getting philosophy". Eventually they just stop moving altogether, gradually "decomposing" or eroding into an oddly-shaped heap of minerals with a tiny living spark in the center. Many of the Discworld's mountains are actually very old trolls.
Their scientific or species name (in Latatian) is Stultus Saxum (i.e. "Dumb Rock").
Troll society is based on rocks and hitting people. They have numerous gods, all of whom bless their worshippers by hitting them on the head with a rock. Trolls believe in a heaven located underground, possibly because of a philosophizing troll's tendency to become part of the landscape. Troll courtships generally consist in the male troll hitting the female troll on the head with a suitably attractive rock followed after that by a candle lit dinner for two with a human as main course (although it is no longer considered polite to eat humans). Some female trolls, through contact with other races, have taken a more feminist approach to courting and now hit the males that they have chosen.
Troll society consists of numerous tribes, with frequent fights between them (although to trolls, this would be a spirited argument). They can only be united by a Diamond King.
Trolls tend to be named after rocks, minerals and geological features, such as Detritus, Flint, and Mica, to name a few. This is used to make puns and jokes on popular real people such as Cliff (Cliff Richard) and Rock (Rock Hudson). Female trolls tend to be named for precious stones, such as "Jade" or "Ruby."
One of the more sophisticated aspects of Trollish culture is their traditional view of time. As the past, where we have been, can be 'seen', whereas the future, where we are going, lies in front of us, they logically conclude we are going through time facing backwards. Also, since they are a nocturnal race, the trollish equivalent of the "Dawn of Time" is the "Sunset of Time."
Some troll tribes play a game called aargrooha, which is rather a lot like soccer. The game involves kicking a human head around on a field with obsidian boots until one side scores a goal or the head bursts, although civilized trolls claim to never play this game anymore (they can't make the boots).
Other known games include a boardgame somewhat similar to chess, in which players set pieces on a board and wait for them to move of their own accord, and a game consisting of throwing rocks in the air and betting on whether or not they will come down. Troll games as a whole are stated to be closely bound up with troll religion and sometimes rather difficult to understand. There is also the Troll/dwarf game of Thud.
Trolls normally express themselves in a very physical way, and according to Samuel Vimes, trollish is "basically body language, and they like to shout". However, they do have a spoken language, although the extent to which it is used commonly among the different tribes is unknown. Troll characters appearing in the novels thus far generally appear to speak the same language as local humans as well. "Street troll" is a term used to refer to the slang version of Morporkian spoken by city trolls. Known trollish words include:
This sample reveals only twelve letters in Trollish: a, g, h, k, l, n, o, p, r, t, u and w.
Many non-trolls stereotypically assume that trolls are either illiterate/innumerate or barely not. This, like many stereotypes, is untrue.
Trolls may have the oldest written language on the Disc. Samples of troll pictograms engraved on basalt slabs have been found in rock layers dating back 500,000 years. A sample translation of these ancient pictograms, found in Thud!, reveals a very isolating grammatic structure.
Trolls have a numeral system of their own, based on powers of 4. The base numerals are one (1), two (2), three (3), many (4) and lots (16), which can be combined to form higher numbers. When combined, each numeral's value is added to those of the others. Higher-valued numerals take priority over lower-valued ones, so that 4 is written "many" and not "two-two" or "three-one" and 20 is written "lots many" rather than "many many many many many". If there are no ones, twos or threes, the number is written with spaces between the numerals; if any exist a hyphen replaces the space between every numeral. With only the revealed numerals the system rapidly becomes unwieldy in higher numbers (for example, one hundred twenty-six in English becomes lots-lots-lots-lots-lots-lots-lots-many-many-many-two in trollish numerals, assuming that they do not have numerals higher than lots), but this may not bother the trolls.
Some trolls, particularly musicians, prefer to count "one, two, many, lots", although how they continue from there is unknown, even to some of them. For example, Jade in Monstrous Regiment says she "ran outa numbers" at that point.
In Men at Arms, Detritus was able to count in a purely binary system after some teaching by Cuddy the dwarf ("A sixteen, an eight, a four and a one"), possibly a joke relating to their silicon brains, and invented higher forms of mathematics while locked in a cold-storage warehouse, although this hasn't been observed on any other occasion; Detritus may simply be an extremely smart troll, or he may conduct cold well. (It is interesting to note that under the same circumstances, Chrysophrase, who is implied to be one of the smartest trolls on the Disc, still spoke poorly. Samuel Vimes theorizes that he did this solely to try to keep him off guard.)
Troll society is unsophisticated, but some trolls in urban areas such as Ankh-Morpork manage to direct their tendency towards violence in more civilised directions. Many trolls have joined the City Watch, beginning with Sergeant Detritus. Others have found a niche in the opposing profession; there is a troll organised crime family called the Breccia, led by the "Ton" Chrysoprase.
Trolls and dwarfs have an ongoing feud, ostensibly stemming from one being a race of living rocks, and the other being a race of miners. But really, this feud goes on because it is a tradition strongly ground into the cultures of both races. Representatives of both races have, however, been known to get along very well, especially in the case of Detritus and Cuddy, but this is rare. In the novel Thud! it is revealed that Koom Valley, the famous troll/dwarf battle, was actually an attempt to sign a peace treaty between dwarfs and trolls and in this novel the tensions grow weaker.
Discworld yeti are a kind of troll, dwelling in the high Ramtops. They are noted for having thick, white, insulating rock-based fur, and large feet, which are considered an aphrodisiac in the Agatean Empire. At least some tribes are unaware that attempting to eat humans is considered inappropriate these days. Yetis have a hunting technique of lying still in the snow until their prey was near them, then pouncing.
The most surprising thing about yeti is their ability to manipulate time. A Yeti can "save" its life up to a certain point and, at the point of death, can return to that point, with the knowledge of what was going to kill it (a clear reference to video games – Terry Pratchett is known to be a gamer). According to the History Monks, the entire species has been rendered extinct three times.
One species considered a relative of trolls are gargoyles. Gargoyles are either urban trolls who formed a symbiosis with guttering, or pieces of stonemasonry initially brought to life by accident, or perhaps by the standing magical field of the Unseen University. They are mainly filter-feeders, but also consider pigeons to be a particular delicacy. Many are employed by the Ankh-Morpork Watch, and more recently by the Grand Trunk Semaphore Company (the clacks), due to their ability to stay in one place watching for long periods of time. They have no concept of money, and are paid in pigeons. A gargoyle's personal identity is closely tied into its normal location; one example answered to the name of "Cornice-Overlooking-Broadway". Most gargoyles are unable to close their mouths, and consequently have some trouble pronouncing many human phonemes (consonants in particular). Apart from this, they are quite capable of understanding and speaking Morporkian.
Another relative to the troll is the Gnoll, which resemble a humanoid with a compost heap strapped to their back, and seem too organic to really be a kind of troll. It has been suggested that they have the same relationship to soil as trolls have to rock, though nobody seems to want to do an in-depth study. They are scavengers of anything that doesn't struggle, although there are rumours. Nobody has really closely enquired into what it is they scavenge. Many of the gnolls in Ankh-Morpork work for Harry King, collecting rubbish for recycling, although they have to be watched to ensure they don't eat it.
It isn't known why Gnolls hoard rubbish. One possible reason is that collectors of carefully sorted kinds of faeces are held in high renown among the gnoll community. Another is simply that they are saving it for later.
While Tethis was in the Potent Voyager along with Twoflower at the end of The Colour of Magic, he is not in the ship in the sequel, The Light Fantastic, and no mention is made of him or his fate. It is possible that the universal reshift at the beginning of that book returned him home.
See Discworld gods
According to The Discworld Companion, there exist, in addition to humanoid trolls, troll dogs, troll horses and troll ducks (although the ducks tend to sink a lot). However, none of these have been seen in the novels thus far.
Eventually, Sergeant Detritus of the City Watch takes in Brick and seems to unofficially adopt him. Detritus was convinced of Brick's potential after Brick was found still conscious, and, what's more, still walking after having a few mugs of a potent troll beverage, the name of which translates to Big Hammer.
See: Detritus (Discworld)