The main advantage of the PHP variable declaration is, it does not requires to specify the data type keyword separately such as int, char, float, double or string etc.

(i) The var_dump( ) function is used to dump information about a variable.
(ii) This function displays structured information such as type and value of the given variable.

Client	Server
(i) A client machine is a small computer with a basic hardware configuration.	A server machine is a high-end computer with an advanced hardware configuration.
(ii) A client is a simple and less powerful machine.	A server is a powerful expensive machine.
(iii) A client is used for simple tasks.	A server is used for storing huge data files and applications.

Web scripting languages are classified into two types.
(i) Client side scripting language
(ii) Server side scripting language.

(i) Webserver is software which is running in server hardware.
(ii) It takes the responsibilities for compilation and execution of server side scripting languages.

(i) PHP can be easily embed with HTML and other client side scripting language like CSS [cascading style sheets) and Java scripts.
(ii) It also creates dynamic and interactive webpages in the real time Web development projects.
(iii) It is competitor of ASP and JSP.
(iv) 78.9% of websites are developed by PHP.

(i) The var_dump( ) function is used to dump information about a variable.
(ii) This function displays structured information such as type and value of the given variable.
(iii) Arrays and objects are explored recursively with values indented to show structure.
Example:
\($\)x = "COMPUTER APPUCATION!";
\($\)x = null;
var dump(\($\)x);
?>
OUTPUT: NULL

(i) Open Source
(ii) Case Sensitive
(iii) Simplicity Program language
(iv) Efficiency Program language
(v) Platform Independent Program language
(vi) Security Program language
(vii) Flexibility Program language
(viii) Real-Time Access Monitoring Program language

Operator is a symbol which is used to perform mathematical and logical operations in the programming languages.
Different types of operators in PHP are:
(i) Arithmetic operators
(ii) Assignment operators
(iii) Comparison operators
(iv) Increment/Decrement operators.
(v) Logical operators and
(vi) String operators
1. Arithmetic operators perform arithmetical operations such as addition, subtraction, multiplication and division etc.
2. Assignment operators are performed with numeric values to store a value in a variable. Default assignment operator is "="
3. Comparison operators perform an action to compare two values.
4. Increment/Decrement operators are used to perform increasing (or) decreasing variable's value.
5. Logical operators are used to combine conditional statements.
6. String operators are two operators which are used to perform string related operations such as concatenation and concatenation assignment.

In two ways we can embed PHP code in HTML page.
(i) First way is to put HTML outside of our PHP tags.
(ii) Second way to use HTML with PHP code is by using print or Echo statement.

(i) A web server's main purpose is to store web files and broadcast them over the internet for you site visitor's to see.
(ii) In-essence, a web server is simply a powerful computer that stores and transmits data via the internet.
(iii) When someone visits a web page on your site their browser communicates with your web server, sending and receiving information that ultimately dictates what appears on the visitor's computer screen. Thus, the main purpose of a web server is to store and transfer web site data upon the request of a visitor's browser.

(i) Server side scripting languages is used in web development.
(ii) It is alternative for web server and itself to deliver a static web page.
(iii) It is used to provide customized interface for the user.
(iv) It also enables the website owner to hide the source code.

Default Syntax:
The default Syntax begins with " < ?php"and closes with "? > ".

Short open Tags
(i) The Short open Tags begins with " < ?" andcloses with "? > " .
(ii) But admin user has to enable Short style tags settings in php.ini file on the server.

HTML Script embed Tags:
HTML Script embed Tags looks just like HTML scripts tags.

An operator is a symbol that performs a given action on a value or group of values. The values the operation is performed upon are known as operands.
The types of operators in PHP are
(i) Arithmetic operators
(ii) Assignment operators
(iii) Comparison operators
(iv) Increment/Decrement operators
(v) Logical operators and
(vi) String operators
1. Arithmetic operators
Arithmetic operators are used to perform math operations, for example, addition, subtraction, multiplication, and division.

Operator	Operator Name	Example	Output
+	Addition	5+2	7
-	Subtraction	5-2	3
*	Multiplication	5*2	10
/	Division	5/2	2.5
%	Modulus	5%2	1

2. Assignment operators
The assignment operator is used to assign a value to a variable. The assignment operator takes the value of its right-hand operand and assigns it to its left-hand operand.

Operator	Operator Name	Example	Output
=	Assignment operator	$a = 5;	5

3. Comparison operators
Comparison operators are used to compare two values and determine whether a certain condition is true or false.

Operator	Operator Name	Example	Output
>	Greater than	5 > 2
<	less than	5<2	False
>=	Greater than or equal to	5>= 2	True
<=	Less than or equal to	5<=2	False
==	Equal to	5==5 5 == 5.0	True False
===	Identical	5===5 5===5.0	True False
!=	Not equal	5!=5 5!=6	True False
!==	Not identical	5!==5 5!==5.0	True False

4.Logical Operators:
Logical operators are used to perform logical operations on variables and values.

Operator	Operator Name	Example	Output
&&	Logical AND	(5>3) && (5>7)	False
II	Logical OR	(5>3) II (5>7)	True
xor	XOR	(5>3) xor (5>7)	True
!	Logical NOT	! (5>3)	False

5. Increment and Decrement operators
In PHP, the increment operator ++ is used to increase the value of a variable by 1, and the decrement operator is used to decrease the value of a variable by 1. The increment and decrement operators can be used as either prefix or postfix operators.

Operator	Name	Output
++ (increment operator)	++ $a Pre-increment	$x = ++ $a
++ (increment operator)	$a + + Post-increment	$x = $a ++
-- (decrement operator)	--$a Pre-decrement	$x = --$a
-- (decrement operator)	$a-- Post-decrement	$x = $a--

6. String operator

String operators have concatenation operator(.) and concatenation assignment operator(-). Concatenation means adding one or more variables to an existing variable.

Operator	Name	Example	Output
. (Dot)	Concatenation	$a = 'Hello'; $b = 'World'; $c= $a. $b;	Hello World
.= (Dot equal to)	Concatenation	$a= 'Hello': $b = 'World'; $a .= $b;	Hello World