Variable declaring in PHP.

Variable: 

Variable is a typical name connected with a quality and whose related worth may be changed. 

For Example: 

txt=a; 

txt=b;[here txt is a variable and "an" and "b" is value.] 

A few standards for PHP variables: 

• A variable begin with "$" sing, trailed by the name of the variable. 
• 
  
• Variable name must begin with a letter or underscore character. 
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• Variable name can not begin with a number. 
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• Variable name can just contain alpha-numeric characters and underscores
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• Variable names are case-delicate.

Variable declaring in PHP:

<?php

$txt=a;

echo '$txt';

?>