A single quote or string literal can be used in PHP to declare a String, ignoring all variables names inside. It may also contains a double quote inside of it. A double quote on the other hand - still declaring a String - accepts variable names to be passed inside, preventing the need for concatenation. A single quote also does not parse escape sequences such as \n and \r. Is there a performance difference between the two types of String Literals? Why not use a double quote all the time and simply escape other double quotes if they are required in the String. Besides outputting variable names I don't see the point in having two strings.

Personally I mostly use double quotes as my default choice when creating Strings unless I need to display a lot of text that contains quotations. In the latter case if there isn't much text I will escape the double quotations but otherwise I would just use single quotes.

I was just wondering if there was a reason (besides displaying variable names) for PHP to have multiple methods to declare a String.