As the cosmere implies a simultaneaous existence of the ten Shardworlds (planets with mentionable Shardic Influence), cosmere books are connected by an overarching story.
Once there was the mysterious power Adonalsium, whose true characteristic is still unknown. Due to unrevealed happenings in the cosmere the Shattering took place, which splintered Adonalsium in - suggested - sixteen Shards each one of them holding a part of the original power of Adonalsium. They then inhabited the ten Shardworlds across the Cosmere inter alia being responsible for the several magic systems on each planet.
In addition to the ten core worlds, there are also untold number of other inhabited worlds in the cosmere, with either no Shardic Influence, or only a Splinter of a Shard. While the cosmere has the same structure as our universe, with galaxies, solar systems, and the like, all of the Shards and Shardworlds are located within the same compact dwarf galaxy, so there are much fewer stars and solar systems than in our own.
Time flows the same on all Shardworlds. The Timeflow is being manipulated by an external force.
Note that there is no need to know anything of the Cosmere to enjoy the Cosmere books and series separately, since its story is told in background.
 Other Relations
The structure of the Cosmere is explained by the Realmatic Theory.
Up until now, six of confirmed ten planets of the main story cycle are known and connected to published and announced books. There are several other worlds now known.
|Ashyn||Unknown||The Silence Divine|
|Braize||Odium||The Stormlight Archive|
|Roshar||Honor, Cultivation||The Stormlight Archive|
|Scadrial||Preservation, Ruin, Harmony*||Mistborn series (including Mistborn Adventures)|
|Sel||Devotion, Dominion||Elantris & sequels, The Emperor's Soul|
|Taldain||Unnamed Shard held by Bavadin||White Sand|
|Unknown||Unknown||Shadows for Silence in the Forests of Hell|
|Unknown||Unknown||Sixth of the Dusk|
- ↑ Are you going to cameo in the Cosmere?
- ↑ The Way of Kings Epigraph 11
- ↑ Physical structure of Cosmere
- ↑ http://new.livestream.com/92Y/YAFantasy/videos/34988457 min 55:33
- ↑ Tell me something new about the Cosmere.
|Shards||Cultivation · Devotion · Dominion · Endowment · Honor · Odium · Preservation · Ruin · Bavadin's Shard · Survival Shard|
|Shardworlds||Ashyn · Braize · Nalthis · Roshar · Sel · Scadrial · Taldain · Yolen|
|Terms||Adonalsium · Sliver · Splinter · Realmatic Theory · Intent · Focus · Investiture · Shardpool · Spiritweb|
|Other||Hoid · Seventeenth Shard · Chronology · Shattering · Worldhopping|