my provides static binding.
local our provides dynamic binding.

Both have their uses. The latter would allow me to set $Carp::Verbose for just one call to carp, for example.

{
   local $Carp::Verbose = 1;
   carp(...);
}
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(Mind you, not a good example, since I could just have called croak.)

And just to show that it works:

sub bar {
   print our $var, "\n";  # Prints 2
}

sub foo {
   local our $var = 2;
   bar();
}

our $var = 1;
foo();
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