Query Strings???

ok can someone explain to me like what query strings are about?
like instead of have POST as a form type to GET?

like what does this mean? and do i need to use the mySQL to use this all together

the list.php3?num=1

????

1) POST allows for more data to be sent and hides the data in the query string from the user.

2) variables passed from page to are accessible in php by the variable name.

example:
list.php3?num=1

variable num can be access in a php script as $num.

This is done between PHP & Apache, mysql isn't needed for this to occur.

so, lets say i have uhm varibles : var1, var2, var3...

how do i get the vars from the url?
if
the script is something like

$var_val1 = $var1 2;
$var_val2 = $var2 3;
$var_val3 = $var3 * 4;

echo("$var_val1 , $var_val2 , $var_val3");

would these varibles be grabed from the url?

no, because the variables are being sent to the browser in the html. variables are sent in a POST or GET ( "mypage.php?var1=val1&var2=val2" )