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Values in Perl are: 1) numbers, 2) strings, or 3) undef.

1. Numbers can use: decimal points, plus or minus signs, and power-of-ten indicators. For example:

     0
     2002
     -40
     255
     61298040283768
     1.25
     255.000
     255.0
     7.25e45           # 7.25 times 10 to the 45th power
     -6.5e24           # negative 6.5 times 10 to the 24th power
     -12e-24           # negative 12 times 10 to the -24th power
     -1.2E-23          # same as above (uppercase E is OK)
   

   For non-decimal representation, we use a leading 0 for octal (base 8), leading 0x for hexadecimal (base 16), and a leading 0b for binary:

     0377              # 377 octal, same as 255 decimal
     0xFF              # FF hex, also 255 decimal
     0b11111111        # also 255 decimal
   

2. Strings are sequences of characters. Inside single quotes, they are exactly the characters printed. To put a single quote inside a string, use a leading backslash. To include a backslash character before a single quote, use two backslashes. For example,

     'abc'             # three characters: a, b, and c
     ''                # the null string (no characters)
     'There\'s a single quote character inside single quotes'
     'The last character is a backslash: \\'
     'hello\n'         # hello followed by backslash followed by n
     'hello
     there'            # hello, newline, there (11 characters)
   

   Inside double quotes, the backslash is used to specify control characters.

     "abc"                 # same as 'abc'
     "Hello, world!\n"     # Hello, world! and a newline
     "The last character is a double quote mark: \""
   

3. undef is the value of variables before they are first assigned. It acts like a 0 or empty string.

To make a list of values, we use comma delimiters between parentheses:

  (1, 2, 3)        # list of three values: 1, 2, and 3
  ("abc", 4.5)     # two values:  "abc" and 4.5
  ()               # empty list
  (1..100)         # list of 100 integers