Important Details (Roshar)

The Greatshell is a type of large crustacean-like creature, occupying many different environments on Roshar.
Greatshells have antennae, shells, and violet blood that smells like mold. Many Greatshells are far larger than any crustacean should be able to grow. This, in part, is due to Roshar's gravity being significantly weaker than that of Earth (greater amounts of oxygen in the atmosphere could also be a contributing factor). Additonally, Greatshell's posses some sort of connection with a special kind of spren. At the center of every greatshell is a massive, uncut gemstone called a gemheart. It is not clear whether the gemhearts actually function analogously to hearts.

Types of greatshell include:

Chasmfiends live inland, in the chasms of the Shattered Plains. They can grow as large as fifty feet tall, have massive claws, an incredibly thick, stone-like carapace, and mouths full of barbed mandibles. They have large gemhearts.

Lanceryn were the only known source of large gemhearts to the Alethi, before the discovery of Chasmfiends. They are presumed to have died off during the Scouring of Aimia.

Chulls are common small shells.

Additionally, off the coast of Marabethia, in the depths, live aquatic greatshells known for their succulent flavor. Many of the Reshi Isles are not actually islands, but island-sized greatshells
Most creatures on Roshar are shelled in some way, to protect against Highstorms.

Spren:
Spren are creatures of nature. With the exception of Shinovar, where there are no spren, they are a common sight all over Roshar and tend to be ignored. Spren are not fully understood. They take different shapes and forms, appearing around certain events, ideas, or abnormalities. Some spren live in Shadesmar, the Cognitive Realm.
They also have their own names, that don't necessarily relate to the name that Roshar inhabitants gave them.

List of names for known spren on Roshar and in Shadesmar:
Alespren
Angerspren
Awespren
Anticipationspren
Bindspren
Captivityspren
Chasmfiend Spren
Coldspren
Creationspren
Deathspren
Decayspren
Exhaustionspren
Fearspren
Flamespren
Gloryspren
Groundspren
Heatspren
Honorspren
Hungerspren
Laughterspren
Liespren (Cryptics)
Lifespren
Logicspren
Luckspren
Musicspren
Nightspren
Painspren
Passionspren
Rainspren
Riverspren
Rotspren
Shamespren
Starspren
Stormspren
Truthspren
Voidspren
Windspren

Whilst many spren appear to do nothing but gather around whatever they are named after, some people think that the spren cause the things they're named after rather than the other way around. For instance, many believe that rotspren cause infection in a wound, as opposed to gathering as a sign that there is an infection present. Spren are typically amorphous and often change in size, luminosity, and shape. Spren can exist for thousands of years and they can die.

Parshmen:
Parshmen are a form of parshendi, common to Roshar and used as servants. They are regarded by their parshendi brethren as slave form, with no soul. The parshmen have black skin mottled with red tones, they are not of a muscular build and appear almost completely mute.
They work as servants throughout Roshar performing menial labour tasks. Parshmen almost never speak although they are able to. They appear to be docile and controlled. It is said they are made to serve, and that if one was to leave a parshman in the woods he would simply sit there until someone came along to tell him what to do.
They hold a particular horror of the tampering with their dead, much like their Parshendi kin.
Despite not being very vocal they often hum a tune to themselves as they work and appear to have a possbile form of telepathic ability to communicate with each other, evidenced by two parshmen working separately humming the same tune in time with each other.

Currency:
Currency on Roshar is based on spheres; little glass beads embedded with gemstones of various sizes. The glass portion of most spheres are the same size; the size of the gemstone at the center of each determines its denomination.
Spheres are glass beads, a little larger than a person's thumbnail with a much smaller gemstone set within its center. Most spheres are also flattened on one side, to keep them from rolling away when set down. pheres are a practical currency. The gemstones within them absorb Stormlight infused during Highstorms and they will stay infused for about a week. The Stormlight within them causes the spheres to glow, turning them into a cheap, rechargeable, mobile light source commonly used for illumination everywhere. Such infused Stormlight is also used to power various Fabrials.
The size of a gemstone and its type greatly influence its value; the larger the stone, the more Stormlight it can gather and the more powerful its effects will be. Different types of fabrials require different types of gemstones. For example, emeralds are most valuable, since they can be used by Soulcasters to create food.
Spheres which run out of Stormlight are called dun spheres. Infused spheres are not worth any more than dun spheres, though sometimes dun spheres are suspect because it is more difficult to see the gemstone inside them, and sometimes a moneylender would have to be brought in to judge the authenticity of a gemstone.

The size of a gemstone inside a sphere determines its denomination. Gemstones come in three denominations: chips, marks and broams. There are five chips to a mark, and four marks to a broam

Broam-- Equal to four marks, or twenty chips/ Provides the light of several candles.
Mark-- Equal to five chips/ Provides a little less light than a candle.
Chip-- one chip/ Provides visible light far fainter than a lamp.

Diamond--clear / 1 diamond chip 5 diamond chips 20 diamond chips
Garnet-- blood / 5 diamond chips 25 diamond chips 100 diamond chips
Ruby--fire / 10 diamond chips 50 diamond chips 200 diamond chips
Sapphire--sky / 25 diamond chips 125 diamond chips 500 diamond chips
Emerald-- / 50 diamond chips 250 diamond chips 1000 diamond chips

The relative values of some gems are unknown, but it is certain that emeralds are worth the most, and diamonds the least, both due to their relative use in Soulcasting; emeralds are used to make food, while diamonds are used to make crystal, glass, and quartz.

On to the 'magic'
Stormlight:
Stormlight is a radiant energy given off by high storms that can be stored in gem stones and then later used by surgebinders or soulcasters. Stormlight is a source of light and power and is used to power the technology of Roshar. Gemstones are much better at holding Stormlight than other objects because the light can remain within them for weeks. Usually, those gemstones kept in spheres (the currency on Roshar), can be infused with Stormlight by leaving them outside during a Highstorm. Infused spheres can also be obtained from money exchangers. Stormlight leaks quickly when held by a Surgebinder or infused into an object other than a gemstone, though persons can slow the leakage by holding their breath (which they can do for an extended time while holding the light).
Stormlight is used by all Surgebinders to perform certain feats, which are akin to those performed by the Knights Radiant, which had 10 Orders. Each Order possessed different abilities. However, stormlight can be used by any Surgebinder to increase battle reflexes, reactivity, speed, and strength.
Stormlight can be used by Windrunners to perform the three types of Lashings (Basic, Full, and Reverse. See Surgebinding.)
It can be used by Lightweavers to create illusions with light

Surgebinding:
Surgebinding is a magic system which involves ten types of Surges, the surges being the fundamental forces of nature. A person who can utilize Stormlight to bind Surges is called a Surgebinder. By the final days of the Era of Solitude, knowledge of Surgebinding is all but totally lost. Its effects haven't been seen for millennia and histories from times of the Heraldic Epochs, when Surgebinders fought during the Desolations and formed the Orders of the Knights Radiant, are all but nonexistent. Most who are aware of it know it mainly from inaccurate legends.
Stormlight is drawn from infused gemstones by inhaling and willing it to enter the body. As long as the Surgebinder is holding his or her breath, Stormlight leaks out much more slowly. Surgebinders holding Stormlight can hold their breath for greatly increased lengths of time, with Stormlight sustaining the body in place of oxygen.

Surgebinders also appear to have a natural gift for combat, along with the other powers they possess. Although they trained hard to achieve their current levels of perfection.
There are ten Surges: Adhesion, Gravitation, Division, Abrasion, Progression, Illumination, Transformation, Transportation, Cohesion, and Tension. Their Glyph representations are shown on the Diagram by the small images.

Each Order of Knights Radiant had two Surges associated with it, and each Surge was used by two different Orders. The Order of the Windrunners made use of Gravitation and Adhesion.

Adhesion
The Surge of Pressure and Vacuum. This is the Surge used to perform Full Lashings, binding an object onto another; used by Windrunners and Bondsmiths.

A Full Lashing binds objects together for as long as the Stormlight lasts. It is similar to a Basic Lashing but works on different principles. To create a Full Lashing, an object is infused with Stormlight, then pressed to another object. The two objects become bound together with an extremely powerful bond, nearly impossible to break. In fact, most materials would themselves break before the bond holding them together would. Bindspren may appear near objects held by a Full Lashing.

Gravitation
The Surge of Gravity. This Surge is used for Basic and Reverse Lashings. With it, the Surgebinder is able to change the direction of his/her gravitational pull and its magnitude; used by Windrunners and Skybreakers.

A Basic Lashing creates a change in gravitational pull, temporarily altering the magnitude and vector of gravity affecting an object. More than one Basic Lashing can be applied to an object at the same time, to increase its acceleration in the selected direction. Fractional Basic Lashings are also possible; a half-Lashing can be used to make an object weightless, and a quarter-Lashing to cut its weight in half.

A Reverse Lashing gives an object a gravitational pull, causing other objects to be drawn to it like to a magnet. This Lashing requires the least amount of Stormlight. It is much more difficult to have items that are on the ground pulled to this object because of the strength of the bond they have with the ground. It is easier to pull items in the air or mid-flight, for example pulling arrows towards a shield or bridge.

Division
The Surge of Destruction and Decay. It's currently unknown how this Surge works, but it seems to be able to cause spontaneous combustion; used by Skybreakers and Dustbringers.

Abrasion
The Surge of Friction. With it, the Surgebinder can make the touch of their body near friction-less (i.e.: enabling them to glide across a floor as if it were slippery ice). It may do other things as well; used by Edgedancers and Dustbringers.

Progression
The Surge of Growth and Healing, or Regrowth. This Surge can exponentially speed and manipulate plant growth. At advanced stages, it also enables the Surgebinder to heal other persons, in an immensely increased version of normal Stormlight healing, capable of bringing someone back from the brink of death; used by Edgedancers and Truthwatchers.

Illumination
The Surge of Light, Sound, and Various Waveforms. It's used to create illusions, both visual and auditory; used by Truthwatchers and Lightweavers.

Transformation
The Surge of Soulcasting. The ability to change matter without a Soulcaster. Initially, it is restricted to the Ten Essences. But, with experience, the Soulcaster can perform more intricate and complex transformations using the Essences as a basis; used by Lightweavers and Elsecallers.

This Surge has been able to be reproduced with a technology called Fabrials, of which the Ardentia makes use.

This ability is unique among the powers of the Knights Radiant as it is the only ability that is affected by the type of gem used to power it. For example, if a Surgebinder wanted to soulcast something into stone, s/he would have to use a topaz to enter Shadesmar.

Transportation
The Surge of Motion and Realmatic Transition. There are rumors that this Surge allowed the Radiants to teleport - to instantaneously transport themselves to another location; used by Elsecallers and Willshapers.

Cohesion
The Surge of Strong Axial Interconnection. Little is known about how this Surge works; used by Willshapers and Stonewards.

Tension
The Surge of Soft Axial Interconnection. It is still unknown just how this Surge works; used by Stonewards and Bondsmiths.

Surgebinders need to have linked to a specific spren in order to use their powers effectively.

Soulcasting:
Soulcasting is the art of changing one substance to another. It is a form of Surgebinding. Soulcasters is a colloquial name for both a person who possesses soulcasting ability and a type of fabrial that allows anyone to soulcast.
Soulcasting is used for a variety of purposes including food production, construction and repair, healing, and killing. The term 'Soulcaster' can refer either to the individual who can Soulcast or the fabrial that most Soulcasters require in order to Soulcast successfully. Almost all Soulcasters are part of the Ardentia and need a fabrial to Soulcast.
Soulcasting fabrials can be attuned to particular Essences, but they can theoretically work with all of the Essences.

Wow.. I actually read it all. Only took me 10 minutes.