Working of PHP scripts
PHP scripts are executed on the server side, meaning they run on the web server before the resulting output is sent to the client’s web browser. Here’s an overview of how PHP scripts work:
1.Client Sends a Request:
A client, typically a web browser, sends a request to the webserver to access a PHP page or file.
The request can be triggered by the user clicking on a link, submitting a form, or making an AJAX request, among other actions.
2.Web Server Receives the Request:
The web server, such as Apache or Nginx, receives the client’s request for a PHP file.
The web server examines the file extension to determine if it’s a PHP file (e.g., .php).
3.PHP Interpreter Executes the Script:
When the web server identifies a PHP file, it passes the file to the PHP interpreter module.
The PHP interpreter reads the PHP script line by line and executes the code sequentially.
4.PHP Code Execution:
PHP code can include a mix of HTML, CSS, JavaScript, and PHP instructions.
PHP instructions are enclosed within tags.
PHP instructions can access variables, perform calculations, interact with databases, process forms, manipulate files, and more.
PHP code can also include control structures (if-else statements, loops), functions, and class definitions.
5.Dynamic Content Generation:
PHP code can dynamically generate HTML, CSS, JavaScript, or other content.
For example, PHP can retrieve data from a database and embed it within HTML templates to generate dynamic web pages.
6.Output Generation:
As the PHP code is executed, it generates output, which can be HTML, CSS, JavaScript, or other types of data.
The output can include dynamic content, variable values, HTML markup, or error messages.
The output generated by PHP is typically combined with static content (such as HTML and CSS) to form a complete web page.
7.Server Sends the Response:
Once the PHP script finishes execution and generates the output, the web server sends the response back to the client.
The response includes the resulting HTML, CSS, JavaScript, or other content generated by the PHP script.
8.Client Receives and Renders the Response:
The client’s web browser receives the response from the web server.
The browser interprets the received HTML, CSS, and JavaScript, and renders the web page accordingly.
If the PHP script generated dynamic content, it will be displayed on the web page.
This process repeats for each request to a PHP script. The server-side execution of PHP scripts allows for dynamic content generation, database interactions, and complex logic, enabling the creation of interactive and personalized web applications.