I am vaguely aware that trolls as described in Norse folklore were NOT hundreds of feet tall, as certain works of literature have it - I also know 'troll' was sometimes used as a euphemism for a pagan, someone who was not Christian, though this was presumably later, once Norse-speakers had largely been converted to Christianity. What role did trolls really play, what did they look like and what did they act like?
There is at least one built-in problem with this question, namely, what the term "troll" means and meant. It is a ubiquitous term in modern Scandinavian languages. It can refer to supernatural beings in a generic way, but it can also refer to different specific types of supernatural beings depending on the language. These can range from very large monsters to smaller supernatural beings more akin to elves - again depending on the location and the language.
I imagine that you're asking about ogre-like supernatural beings as they made the transition from their pre-conversion antecedents to entities in modern recent folk belief systems. Because many trolls are big, they were often confused with giants.
In modern English literature, trolls and giants are nearly interchangeable, largely because speakers of English rely so heavily on the huge Norwegian troll for their concept of what the supernatural being was like. Even in Scandinavia, trolls and giants occasionally shared some characteristics. Distinguishing between the two is an important first step in understanding the rich folklore that surrounded the troll.
Most importantly, people did not tell stories about actually seeing giants. In this respect, giants are similar to the more abstract nature spirits and gods. The folk concluded giants had existed as a consequence of an intellectual form of deduction, in the same way that they considered spirits or gods to be real. People believed giants existed based on the existence of something unusual in their immediate environment. A famous example of this is preserved in the name of Northern Ireland’s “Giant’s Causeway.” Here, people regarded a peculiar rock formation as the ancient work of a large supernatural being. Later residents near England’s Devil’s Dyke in Cambridgeshire saw the long prehistoric earthwork as superhuman, crediting it to Satan. Though the devil is not a giant, his English dyke represents the same process of attributing a remarkable thing to a supernatural being’s effort long ago.
This discussion may or may not be what you're after. Given some of what I have written here, perhaps you can speak specifically as to what you seek.
Troll is, as far as I understand, a fairly new term that originally was a catch-all for all the supernatural beings that, under Christianity, were regarded as being just different faces of the devil and his minions anyway, but still retained enough of their original personalities to not be just faceless devils and not necessarily actively evil all the time.
Originally, what became "trolls" were thus huldre, nøkk, jotner, svartalfer, ljosalfer, dvergar, and others. Even the vaner and æser gods probably became demoted to "trolls" in may folktales. It is important to remember that the old Norse belief system never was codified and thus varied a lot over time, between different places and even individuals. Especially after the active cults were suppressed by Christianity and it all became half-remembered tales re-interpreted in light of what people now were told was the "truth".
Source: Am Norwegian with a long-standing interest in mythology and old rural relatives.