what is a string?

[Han]

The PRINT() command prints a string by simply displaying its characters. A string is just a sequence of characters. It does not include the double-quotes.

The double-quote is simply used for display purposes as well as for enabling users to specify that the sequence of characters is a string. Without it, how else would a user be able to distinguish the number 123 vs. the string 123 if all that is shown in the screen is 123? So this is why the calculator will display "123" instead of just 123. The same goes for creating strings, etc.