Newbie with RegEx question

[MarkyMoon]

Hi everyone,

 Now that things are starting to make a little more sense to me,
I've been going through the llama book (again) and I'm having a bit
of a problem understanding why 

(abc)* 

will match a null set  "" (in addition to abc,abcabc, abcabcabc
etc.)... and WHY would you WANT to define a pattern that has the
possiblility of matching nothing? I can't think why that would be
useful. Any hints would be mucho appreciado. This is stated in
section dealing with Regular Expressions:Precedence (page 84). I
keep looking at it but now the page is just getting fuzzy and I may
cry soon.

Thanks in advance,
Mark Smith
-- 
My very first japh's!
(Sure... they're not fancy, but I'm a graphic designer dang-it!)
--

@a = ("a".."z"," ","-","\n");foreach $b (
12,0,17,10,24,12,14,14,13,26,8,18,26,0,26,
22,0,13,13,0,27,1,4,26,15,4,17,11,26,7,0,
2,10,4,17) {print "$a[$b]"};print $a[28];

--numero dos --

@a = ("a".."z"," ",",","\n","!");foreach $b (
28,0,26,14,13,4,26,11,26,17,0,13,3,0,11,26,22,17,14,19,4,26,19,7,4,26,1,14,14,10,27,28,
0,26,19,22,14,26,11,26,11,11,0,12,0,26,5,14,17,26,19,7,4,26,11,14,14,10,27,28,
1,20,19,26,19,14,26,22,7,14,12,26,22,4,26,14,22,4,26,8,19,26,0,11,11,27,28,
8,18,26,19,7,4,26,19,7,17,4,4,26,11,26,11,0,17,17,24,26,22,0,11,11,29,28,28,
17,0,13,3,0,11,28) {print "$a[$b]"};print $a[28];
TIMTOWTDI