The answers above are very good, but what I suspect you're driving at is a strategy for reading regular expressions.

So I'll take a stab at first summarizing, then show you how I would decipher this.

SUMMARY: Is it blank (as seen by a human)? i.e., either has nothing in it, or has nothing but whitespace in it.

STRATEGY:

1) Look at the first and last characters.
1a) ^ on left means "anchor left", meaning the match must be at the start of the string.
1b) $ on the right means "anchor right", meaning the match must be at the end of the string.

EXAMPLE:

my $data = 'This is a test of the anchors.';
if ($data =~ /test/) IS TRUE because "test" does occur somewhere in the string.
if ($data =~ /^test/) IS FALSE because it doesn't start with "test".
if ($data =~ /test$/) IS FALSE because it doesn't end with "test".

2) What's left: \s*
2a) \s means whitespace
2b) * means 0 or more

Hence, 0 or more whitespace characters.

3) Put it back together.

0 or more whitespace characters, which must start at the beginning and finish at the end. Any nonspace character anywhere in the string triggers the else clause.

Thus, in human (and therefore terribly imprecise) terms, "Is it blank?"

Have fun. You do get better at reading regular expressions once you've written a few. However, after all these years, I still have to shake my brain a few times to read the really convoluted ones. :: grin ::

Edit: s/strategty/strategy/