The Wolfram System is a large and complex software system. Although strongly not supported for production purposes, it is sometimes instructive to "spelunk" in the system, looking at low-level organization and obscure features.

Names — complete lists of symbol names matching a pattern (e.g. "*`*")

Contexts — give complete lists of contexts for symbol names

SystemOptions — low-level system options

Show Expression () — show the symbolic structure of notebook contents

Option Inspector — inspect lists of front end options

Options — get a complete list of options for $FrontEnd

Trace — trace every step in the evaluation of an expression

Stack — show the state of the complete evaluation stack