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.