Exactly what is the difference between Single Quotation (') and Double Quotation (") in PHP?

Answer 1

Single on are faster, but they are plain text.

Doubles ones search for variables inside , so it takes a bit longer.

$World = 3;
echo " Hello $World"
//output Hello 3

echo 'Hello $World'
//output Hello $World

Answer 2

use html code in single quotation better than double quotation.

Answer 3

Double quotes force PHP to evaluate the string while single is treated as a string literal. So, using single quotes is faster than using double quotes.