The novels that make up the Discworld series are all related, taking place in the same world but with no common story running through all of them. They can be grouped into a number of sub-series, organised by the main protagonists in each one, as well as stand-alone novels and companion books. Characters from one book often have small cameo roles in others, and many of the locations appear in all of the different series.
Rincewind is, without question, the worst Wizard on the Disc (he can’t even spell it properly), and yet has somehow managed to save the world several times through his misadventures. He is cowardly, lazy, and wishes nothing more than to have a quiet life drinking beer and sleeping. He’s often dragged off to the more unexplored regions of the Disc in quests that he wants nothing to do with, and spends a lot of his time running away from things.
Rincewind travels (somewhat reluctantly) with a large chest named The Luggage. It’s sentient, made from the wood of the sapient pear tree, and moves around on hundreds of tiny legs. It’s fiercely loyal to him, often eating any unfortunate barbarians or other enemies that get too close, but only ever seems to have clean laundry inside once opened.
The Death of the Discworld exists as the anthropomorphic personification we expect in our own world. He’s a tall skeleton, dressed in a black robe, complete with a scythe, and a sword (for royalty). This is where the similarity ends, however, as Death has developed a very likeable personality over the eons. He has a house and garden (in another plane of existence), a real white horse named Binky, loves kittens, and enjoys a hot curry (which he describes as like biting into a red-hot ice cube). He never actually speaks; instead, his voice arrives in the listener’s head without ever having passed through their ears.
In his fascination with humanity, he attempts to understand the things that we do by trying them himself, but this has led to some very awkward and dangerous situations. He is never the cause of death in any living thing, but exists only to be there at the end, ensuring that being’s life energy is properly recycled into the universe and can begin again elsewhere.
The Ankh-Morpork City Watch (City Watch or simply The Watch) is the police force of the Disc’s largest city. Its fortunes have waxed and waned over the centuries since its creation, eventually dwindling to the three men of the Night Watch. Their main job was to roam the city streets at night shouting, “Two o’clock and all’s well!” and should it not be well, they found another street. The Watch motto, as inscribed over the Treacle Mine Road watch-house, had eroded to "Fabricati Diem, Pvnc." This changed after the arrival of Lance-Constable Carrot and the events of ‘Guards! Guards!’ with Captain Vimes moving up to Commander and recruiting many more Watchmen, including from other ethnicities such as trolls, dwarves, the undead, werewolves, and even vampires.
Commander Vimes has a somewhat tarnished personality, and often despairs that his own deep cynicism is unmatched by just how cynical the world can be. The Watch is all he has ever known, and he puts all of the things he’s learned in his time as a street copper into the top job.
The Witches of the Disc are almost entirely unlike the Wizards, besides being female, that is. While Wizards like to live in the same huge building (e.g. the Unseen University), eat big dinners together, and occupy positions in an intricate hierarchy, Witches don't have "official" ranks, and don't gather except for a potluck during a necessary meeting to discuss boundaries. These are boundaries not of power, but of duty, for a Witch is generally the midwife, doctor, life adviser, and moral policeman of a village.
A group of Witches is normally referred to as an “argument” and don't stay together, but some covens have stayed together, such as the Lancre Coven in the Ramtop Mountains. The Witches in the Ramtop Mountains are driven more by practicality than performing magic. Chief among all the leaders that they don’t have is Granny Weatherwax, whose power and influence are known far beyond the borders of her territory. Nanny Ogg is another Ramtop Witch but her personality is a polar opposite to Granny’s, with a large family and loving a drink and sing-song.
Tiffany Aching is a young trainee Witch from The Chalk, a farmland area downhill and Rimward of the Ramtop Mountains. She began her training at the very young age of just nine, and grows up through the events of each of the books in the series, being in her late teens by the events of ‘The Shepherd’s Crown’.
Her grandmother was a legendary shepherd, and considered the Witch of The Chalk, even though Witchcraft was generally frowned upon in that area. Granny Aching was a friend of the Chalk's Clan of Nac Mac Feegles (an army of tiny, blue, rowdy, drunken, and vaguely Scottish 'pictsies'), and they have befriended Tiffany as the new "hag o' the hills". As Tiffany was their Kelda (Queen) for a short time, the Nac Mac Feegle see her as their responsibility, and there is no time in Tiffany's life since, when they have not (in)discreetly watched her.
Tiffany’s journey to becoming a Witch takes her through many adventures, including fighting the Queen of the Elves, attracting the romantic interest of the Wintersmith, and also being able to exert limited influence over events throughout the timeline, with the help of Eskarina Smith, the main character of ‘Equal Rites’.
The Industrial Revolution series of books each introduce some new piece of technology to the Disc, which thereafter, feature strongly in all subsequent books across the different arcs. By the end of the series, the Disc has been brought firmly into the technological equivalent of the 19th Century.
From semaphore towers (named 'The Clacks', thanks to the noise they make in operation), to printing presses for the Disc’s first newspaper, to the invention of paper money and steam locomotives; each new piece of technology brings with it benefits and dangers that couldn’t possibly exist anywhere else other than the magical world of the Disc. Who would have thought that the invention of motion pictures might unlock secrets that threaten to destroy the world? Or that newspaper journalism would involve a recovering vampire with a suicidal fascination for flash photography, and, worst of all, the man who keeps begging to have pictures of his humorously shaped potatoes published.