Quotes
you can use echo with single quotation marks to print text. When you do this, everything inside the single quotes is treated as plain text, not code. For example, if you include a variable like $name inside single quotes, it won’t show the value of the variable. Instead, it will display $name exactly as it is written.
Double quotes are not read literally by PHP the way single quotes are, thus allowing us to write code within the phrase that will be printed out by PHP. We can use the same example of the variable $name. When writing $name without the escape slash (as is used in the two previous instances) it will simply be replaced by its pre-defined definition according to the previous PHP code: Chris, Chris, Chris.