These are represented in the registry as subtrees. Furthering our metaphorical comparison, folders and subfolders are comparable to keys in the Registry. Different keys represent different hardware or software objects. There are over a thousand keys in the registry. Files in the folders would correspond to entries.
Entries are what comprise the registry.
Each setting in Windows is an entry in the registry. So this is what the registry would look like. Depending on which version of Windows is on your computer, the Registry editing choice is different. If you are running a 9x version, only one editor, regedit.exe, is included. If you are running NT or 2000, you can either use regedit.exe or regedt32.exe.