Interpolation in PHP is an important feature of PHP. PHP supports interpolation of variables in between number of words to be printed or to be display like output statements echo() and print().
In code we use single quote to define a constant string, like ‘php’ , ‘constant value’ , ‘fix value’ , while using double quote to define a string contain identifier like echo “Price of $b is $c total $d” or echo “my $a”,Where $a,$b,$c,$d are the variable which contain value ,which is not available at the time of coding,but when we execute it on server it will return some value.
To understand how interpolation in PHP works we are taking an example
Now if we use double quote it look like
echo “$a php”; /////output will be Hello php
echo ‘$a php’; /////output will be $a php