As a front-end developer looking to learn PHP, there are several excellent online resources available to help you get started and advance your PHP skills. Here are some of the best online platforms and websites where you can learn PHP:

1. PHP.net: The official PHP website (php.net) provides a comprehensive PHP manual and documentation, which is an excellent resource for beginners and experienced developers alike. It covers all aspects of the PHP language with examples and explanations.

2. W3Schools PHP Tutorial: W3Schools offers a beginner-friendly PHP tutorial that covers the basics of PHP programming, including syntax, variables, loops, arrays, and more. It's a great place to start learning PHP.

3. PHP: The Right Way: This website (phptherightway.com) is a community-driven PHP best practices guide. It offers a practical and up-to-date approach to learning PHP, focusing on modern techniques and industry standards.

4. Codecademy PHP Course: Codecademy provides an interactive and hands-on PHP course where you can learn PHP while writing code directly in your browser. It's a beginner-friendly platform for getting started with PHP.

5. Udemy PHP Courses: Udemy offers a variety of PHP courses taught by instructors from around the world. You can find courses for all levels, from beginners to advanced developers, covering different aspects of PHP development.

6. FreeCodeCamp PHP Tutorial: FreeCodeCamp has a free PHP tutorial that covers the basics of PHP programming, along with exercises and challenges to practice what you've learned.

7. LinkedIn Learning: Formerly known as Lynda.com, LinkedIn Learning offers a selection of high-quality PHP courses taught by industry experts. It's a paid platform, but you may have access through your LinkedIn Premium membership or educational institution.

8. YouTube: YouTube has numerous channels dedicated to teaching PHP, ranging from beginner tutorials to more advanced topics. Channels like "Traversy Media" and "The Net Ninja" are popular for web development content.

9. SitePoint PHP Tutorials: SitePoint's PHP section provides tutorials, articles, and guides on various PHP topics, making it a valuable resource for learning PHP concepts and best practices.

10. Stack Overflow: While not a dedicated learning platform, Stack Overflow can be an invaluable resource for PHP developers. You can search for PHP-related questions and answers, learn from others' experiences, and ask your own questions if you encounter specific issues.

11. PHP Academy: PHP Academy offers free video tutorials covering various PHP topics, ranging from beginner to intermediate levels. Their tutorials provide hands-on examples and practical insights.

12. Learn-PHP.org: Learn-PHP.org is a free and interactive PHP tutorial platform that allows you to practice coding exercises directly in the browser while learning PHP concepts.

13. PHP Classes: PHP Classes (phpclasses.org) is a website that offers a vast collection of PHP classes and tutorials, allowing you to learn from real-world code examples and projects.

14. Coursera PHP Courses: Coursera hosts PHP courses from reputable universities and institutions. While some courses require payment, you can audit many of them for free and access the course materials.

15. SoloLearn PHP Course: SoloLearn is a mobile app that offers a PHP course for beginners, making it convenient for learning on the go.

16. GeeksforGeeks PHP Section: GeeksforGeeks provides PHP tutorials with a focus on algorithms, data structures, and problem-solving using PHP.

17. TutorialsPoint PHP Tutorial: TutorialsPoint offers a comprehensive PHP tutorial that covers all major PHP concepts, including database connectivity and sessions.

18. Code Wall: Code Wall has a collection of PHP tutorials and articles written by developers to help you understand various PHP-related topics.

19. PHP Podcasts: If you enjoy learning through audio, consider exploring PHP-related podcasts like "PHP Roundtable" and "Voices of the ElePHPant" for discussions and interviews with PHP developers.

20. GitHub PHP Repositories: Explore PHP repositories on GitHub to discover open-source PHP projects and learn from the code written by experienced developers.

    Remember that a combination of structured learning through tutorials, hands-on practice, and real-world projects will be most beneficial in mastering PHP. Each resource mentioned above offers a unique approach to learning, so try out a few to see which ones align with your preferred learning style. Happy coding!