Sorcerers, like true Elemancers, draw their energy for spells from their bodies, used as a conduit for the arcane. In general, sorcerers are capable of casting spells from any of the basic elements, but are not restricted to them. Most sorcerers know an eclectic array of spells picked up from others or devised on their own through years of manipulating the arcane. A new spell takes years to devise. An unlearned spell taught by another who already knows it may take weeks or even months.
Sorcerers do not have true access to the Elemental Realms and cannot take on an Incarnate state like an Elemancer. This makes them far less than an Elemancer when it comes to raw power. What they lack in power, sorcerers make up for in versatility.
The rise of sorcerers comes from the fact that any Elemancer who violates their pact with one of the Elemental Realms, does so by successfully attempting to cast a spell that is not of their element, even if the spell is not necessarily elemental in nature. This is rare, but not unheard of. In the past, those fallen Elemancers have had descendants with the innate capacity for magic but without the inherent tie to a specific Realm.
Sorcerers even have the capcity to mimic some Wizard spells the same way they would devise a brand new spell. The same limitations of power and knowledge apply to sorcerers as it does to their cousin spellcasters.
All kinds of people can become sorcerers, although naturally magical kinds like the Fey such as Sylphs tend to have slightly more power, a more subtle manipulation, and a more versitile array of spells than others.