my keyword local and global variables in perl

In Perl, the my, our, and local keywords are used to declare variables with different scoping rules. Here's an overview of each keyword:

1. my: The my keyword declares a variable with local scope. This means that the variable is only accessible within the block of code where it is declared. For example:

sub foo {
  my $x = 42; # local variable
  print $x; # prints 42
}
foo();
print $x; # ERROR: $x is not defined outside of the foo() subroutine

2. our: The our keyword declares a variable with package scope. This means that the variable is accessible anywhere within the package (module) in which it is declared. For example:

package MyModule;
our $x = 42; # package variable
sub foo {
  print $x; # prints 42
}
foo();
print $x; # prints 42

3. local: The local keyword creates a temporary copy of a global variable with local scope. This means that changes to the variable within the block of code where local is used will not affect the value of the global variable outside of that block. For example:

our $x = 42; # global variable
sub foo {
  local $x = 10; # local copy of $x
  print $x; # prints 10
}
foo();
print $x; # prints 42

In general, it's a good practice to use my for most variables, since it keeps variables local to the block of code where they are needed and avoids naming conflicts with other variables. However, our and local can be useful in some cases, such as when working with global variables or when you need to temporarily modify the value of a global variable within a specific block of code.