A string is can have letters, numbers, special characters and arithmetic values or combination of all.
Example: Hello World !
Example: Hello World ! 123
Above both example are string.
To assign a string to a variable is there is two way.
You can use both single quotation or double quotation.But there is a small difference between single quotation and double quotation.
So now in our mind a big confusion come that where to use single quotation and where to use double quotation.
Best example to under stand.
Output: $a World
Output: Hello World