Here’s a primer: https://pmc.ncbi.nlm.nih.gov/articles/PMC3882043/

Also Wikipedia has some models of proteins in their folded and unfolded configurations.

Protein misfolding is now implicated in the progression of hundreds of diseases; indeed, it is involved in the majority of diseases not caused by an infectious agent.

Prions are being mentioned because they are a famous example of contagious misfolded proteins, but really a lot of other diseases are caused by the same basic issue of misfolded proteins.