100 Must-Know PHP Interview Questions and Answers 2025

PHP Fundamentals

1.
What does PHP stand for and what is its main purpose?
2.
How do you execute a PHP script from the command line?
3.
Can you describe the differences between PHP 5 and PHP 7/8?
4.
What are the common ways to embed PHP into HTML?
5.
How would you create a PHP variable and how are they scoped (global, local, static)?
6.
Explain the data types that are supported in PHP.
7.
How does PHP handle error reporting?
8.
What is the purpose of php.ini file?
9.
How do you define a constant in PHP?
10.
Can you describe the lifecycle of a PHP request?
11.
Explain the use of sessions in PHP.
12.
How does PHP support cookies?
13.
Describe the _$_GET, _$POST, and _$REQUEST superglobal arrays.
14.
How can you prevent form submission data from being injected with malicious code?
15.
What is the significance of “htmlspecialchars” and “strip_tags” in PHP?

PHP Advanced Features

16.
Explain late static binding in PHP.
17.
What is a namespace in PHP and why are they used?
18.
Can you describe what a closure is in PHP and provide an example?
19.
Explain the concept of traits in PHP and how they’re used.
20.
How does PHP handle exceptions and error handling?
21.
Discuss type declarations and return type in PHP 7/8.
22.
What is a generator in PHP and when would you use one?
23.
What are anonymous classes and how do you use them in PHP 7/8?
24.
Explain how to use the “yield” keyword in PHP.
25.
Describe the difference between “include”, “include_once”, “require”, and “require_once”.

PHP Functions and Classes

26.
How do you declare a function in PHP?
27.
What are magic methods in PHP?
28.
How are objects passed in PHP - by value or by reference?
29.
What are interfaces and how are they different from abstract classes in PHP?
30.
Explain how you can prevent the class from being inherited.
31.
What are getters and setters, and why would you use them?
32.
Describe method overloading in PHP.
33.
How would you use a static method or property in a class?
34.
What is the purpose of the “final” keyword in PHP?
35.
Discuss dependency injection in PHP.

PHP Database Interaction

36.
How does PHP interact with databases?
37.
What is PDO (PHP Data Objects) and how it is different from MySQLi?
38.
Explain a prepared statement and why it’s used in PHP.
39.
How can you perform a transaction with PDO?
40.
Describe the process of connecting to a MySQL database using PDO.
41.
What mechanisms does PHP provide for accessing NoSQL databases?
42.
How would you handle database errors in PHP?
43.
Can you explain how ORM tools like Laravel’s Eloquent or Doctrine work in PHP?
44.
How does PHP handle database connection persistence?
45.
Explain how you would use PHP to handle multiple database connections.

PHP Security Practices

46.
What is SQL Injection and how can it be prevented in PHP?
47.
How does PHP handle password hashing?
48.
Explain Cross-Site Scripting (XSS) and how to prevent it with PHP.
49.
Discuss prevention of CSRF (Cross-Site Request Forgery) in PHP.
50.
Describe the concept of session hijacking and how PHP can safeguard against it.
51.
How would you secure file uploads in PHP?
52.
What are the best practices for securing PHP applications on shared hosts?
53.
Explain how to securely store sensitive data, such as API keys, in PHP applications.
54.
Discuss the use of HTTPS and how PHP can enforce secure connections.
55.
What are PHP filters and how can they be used to validate and sanitize data?

PHP Performance Optimization

56.
How can you improve the performance of a PHP application?
57.
What is opcode caching and how can it be used in PHP?
58.
Discuss the use of content delivery networks (CDNs) in relation to PHP applications.
59.
How does session storage affect PHP performance and what alternatives exist?
60.
Explain how to profile a PHP application for performance issues.
61.
What is lazy loading and how can it be implemented in PHP?
62.
Discuss the use of indexes in databases and how it relates to PHP performance.
63.
How can PHP leverage browser caching?
64.
What are some common PHP bottlenecks and how do you resolve them?
65.
Describe the concept of connection pooling and its relevance to PHP applications.

PHP Testing and Debugging

66.
What tools can you use for unit testing in PHP?
67.
How do you debug PHP scripts?
68.
What is the purpose of the Xdebug extension for PHP?
69.
Discuss the benefits and methods of integration testing in PHP applications.
70.
How would you set up a staging environment for testing PHP applications?
71.
Describe how assertions can be used in PHP.
72.
What is code coverage and how can it be measured in PHP?
73.
Discuss the role of continuous integration in PHP development workflows.
74.
Explain the “var_dump” and “print_r” methods used in debugging PHP code.
75.
How can you track down and fix memory s in PHP?

PHP Configuration and Deployment

76.
What is the typical workflow for deploying a PHP application?
77.
How does PHP handle file uploads and server file management?
78.
Discuss the various ways you can configure PHP logging.
79.
What are environment variables in PHP and how can they be used?
80.
How would you automate the deployment of a PHP application?
81.
Explain the role of Composer in PHP development.
82.
Describe a virtual host and how it is configured for PHP applications.
83.
How can containerization be utilized in PHP application deployments?
84.
Discuss .htaccess files and their importance in PHP configurations.
85.
What measures do you take to ensure a smooth rollout of new PHP code in production environments?

PHP Modern Development Practices

86.
How has PHP integrated with front-end JavaScript frameworks?
87.
Discuss PHP’s support for HTTP/2.
88.
Explain the use of WebSockets in PHP.
89.
Describe the role of PHP in a microservices architecture.
90.
How does PHP handle REST API development?
91.
Discuss the use of GraphQL with PHP.
92.
What is serverless architecture and can PHP be used in such an environment?
93.
How do modern PHP frameworks handle route-based actions?
94.
Explain how MVC architecture is implemented in PHP.
95.
Describe how PHP can be used for command-line scripting.

PHP Frameworks

96.
What are the benefits of using a PHP framework?
97.
Can you compare Laravel and Symfony?
98.
How would you choose between different PHP frameworks for a project?
99.
Discuss the role of template engines in PHP frameworks.
100.
Explain the event-driven architecture in PHP frameworks like Laravel.

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100 PHP interview questions

What does PHP stand for and what is its main purpose?

How do you execute a PHP script from the command line?

Can you describe the differences between PHP 5 and PHP 7/8?

What are the common ways to embed PHP into HTML?

How would you create a PHP variable and how are they scoped (global, local, static)?

Explain the data types that are supported in PHP.

How does PHP handle error reporting?

What is the purpose of php.ini file?

How do you define a constant in PHP?

Can you describe the lifecycle of a PHP request?

Explain the use of sessions in PHP.

How does PHP support cookies?

Describe the _$_GET, _$POST, and _$REQUEST superglobal arrays.

How can you prevent form submission data from being injected with malicious code?

What is the significance of “htmlspecialchars” and “strip_tags” in PHP?

Explain late static binding in PHP.

What is a namespace in PHP and why are they used?

Can you describe what a closure is in PHP and provide an example?

Explain the concept of traits in PHP and how they’re used.

How does PHP handle exceptions and error handling?

Discuss type declarations and return type in PHP 7/8.

What is a generator in PHP and when would you use one?

What are anonymous classes and how do you use them in PHP 7/8?

Explain how to use the “yield” keyword in PHP.

Describe the difference between “include”, “include_once”, “require”, and “require_once”.

How do you declare a function in PHP?

What are magic methods in PHP?

How are objects passed in PHP - by value or by reference?

What are interfaces and how are they different from abstract classes in PHP?

Explain how you can prevent the class from being inherited.

What are getters and setters, and why would you use them?

Describe method overloading in PHP.

How would you use a static method or property in a class?

What is the purpose of the “final” keyword in PHP?

Discuss dependency injection in PHP.

How does PHP interact with databases?

What is PDO (PHP Data Objects) and how it is different from MySQLi?

Explain a prepared statement and why it’s used in PHP.

How can you perform a transaction with PDO?

Describe the process of connecting to a MySQL database using PDO.

What mechanisms does PHP provide for accessing NoSQL databases?

How would you handle database errors in PHP?

Can you explain how ORM tools like Laravel’s Eloquent or Doctrine work in PHP?

How does PHP handle database connection persistence?

Explain how you would use PHP to handle multiple database connections.

What is SQL Injection and how can it be prevented in PHP?

How does PHP handle password hashing?

Explain Cross-Site Scripting (XSS) and how to prevent it with PHP.

Discuss prevention of CSRF (Cross-Site Request Forgery) in PHP.

Describe the concept of session hijacking and how PHP can safeguard against it.

How would you secure file uploads in PHP?

What are the best practices for securing PHP applications on shared hosts?

Explain how to securely store sensitive data, such as API keys, in PHP applications.

Discuss the use of HTTPS and how PHP can enforce secure connections.

What are PHP filters and how can they be used to validate and sanitize data?

How can you improve the performance of a PHP application?

What is opcode caching and how can it be used in PHP?

Discuss the use of content delivery networks (CDNs) in relation to PHP applications.

How does session storage affect PHP performance and what alternatives exist?

Explain how to profile a PHP application for performance issues.

What is lazy loading and how can it be implemented in PHP?

Discuss the use of indexes in databases and how it relates to PHP performance.

How can PHP leverage browser caching?

What are some common PHP bottlenecks and how do you resolve them?

Describe the concept of connection pooling and its relevance to PHP applications.

What tools can you use for unit testing in PHP?

How do you debug PHP scripts?

What is the purpose of the Xdebug extension for PHP?

Discuss the benefits and methods of integration testing in PHP applications.

How would you set up a staging environment for testing PHP applications?

Describe how assertions can be used in PHP.

What is code coverage and how can it be measured in PHP?

Discuss the role of continuous integration in PHP development workflows.

Explain the “var_dump” and “print_r” methods used in debugging PHP code.

How can you track down and fix memory s in PHP?

What is the typical workflow for deploying a PHP application?

How does PHP handle file uploads and server file management?