Regex geedy and non-greedy match

.* is greedy match
.*? is non-greedy match

PHP example:
$str="abc123abc456abc";
preg_match("/abc(.*)abc/",$str,$match);
echo $match[1]; // result is 123abc456
preg_match("/abc(.*?)abc/",$str,$match);
echo $match[1]; // result is 123