What is $*?

Will display all the commandline arguments that are passed to the script

Its mainly used for showing up all params. 
i.e - if you execute script in following way to which we are trying to pass 4 params 
./test.sh 1 "hello world" 2 "test" 
and if we print inside script 
echo $* 
it will print  
null1 hello world 2 testnull

$1: the 1st parameter 
$2: the 2nd parameter 
... 
$* 
All parameters in the command line 
 

Yes, $* displays values of all positional parameters set

it is a questional parameter

It contains the actual arguments passed to a shell script

Contains the list of arguments passed to the function.