Foldit has many View Options which affect the appearance of the protein. The most basic view options are "show clashes", "show exposeds", and "show voids", which are available in the both the "basic" and "advanced" view options. Various "show bonds" options exist in both versions of the view options, and so do "show bondable atoms" and "show expected residue burials".
Other options, such as "show backbone issues" and "show isosurface" exist only in the advanced version of the view options.
This gallery shows how the view options affect the appearance of the protein.
Spiky red balls highlight clashes with "Show clashes"
Blotchy yellow spheres highlight exposed hydrophobics with "Show exposeds"
Ghostly red blobs highlight voids with "Show voids"
Blue-and-white candy canes show hydrogen bonds with "Show bonds"
Green-and-yellow candy canes highlight disulfide bridges, a special type of bond, with "Show bonds"
Red and blue spheres and tubules highlight hydrogen bond acceptors and donors with "Show bondable atoms"
A red exclamation point highlights non-ideal backbone with "Show backbone issues" (Advanced GUI)
A translucent cloud surrounds the protein with "Show isosurface". A hole in the isosurface extends through the protein. (Advanced GUI)