What does $$, $?, $^ represent in powershell?

Question

Saw these variables in the debugger and I'm not sure what they do.

Answer 1

• $_ The current pipeline object; used in script blocks, filters, the process clause of functions, where-object, foreach-object and switch
• $^ contains the first token of the last line input into the shell
• $$ contains the last token of last line input into the shell
• $? Contains the success/fail status of the last statement

Source: http://www.computerperformance.co.uk/powershell/powershell_variables.htm#%24Dollar_variables_