PHP

1. Basic syntax

   PHP tags, embedding in HTML, statements, comments.

2. Types

   Scalars, arrays, objects, null, type juggling, strict_types and type declarations.

3. Variables

   Variable scope, superglobals, variable variables and references.

4. Constants and operators

   Operator precedence, null coalescing, spaceship, comparison and string/array operators.

5. Control structures

   if, match, switch, loops, foreach, break/continue and include/require.

6. Functions

   Parameters, defaults, named arguments, variadics, return types, closures and arrow functions.

7. Classes and objects

   Properties, methods, visibility, constructors, static, abstract classes, interfaces and traits.

8. Enumerations

   Pure and backed enums, enum methods and interfaces.

9. Namespaces

   Namespace declarations, use imports, autoloading with PSR-4.

10. Errors and exceptions

    try/catch/finally, Throwable hierarchy, Error vs Exception and error handling configuration.

11. Generators

    yield, generator delegation and lazy iteration.

12. Attributes

    Native metadata annotations and reflection access.

13. References

    Reference semantics, passing and returning by reference.

14. Fibers

    Fiber-based cooperative concurrency.

15. Predefined variables and interfaces

    Superglobals such as $_GET, $_POST, $_SERVER and $_SESSION, plus built-in interfaces like ArrayAccess, Iterator and Countable.

16. Sessions and cookies

    HTTP authentication, cookies, sessions, file uploads and request handling.

17. Database extensions (PDO)

    PDO, prepared statements and transactions.

18. Security

    Input validation, SQL injection, XSS, CSRF, password hashing and secure configuration.

19. Extensions and configuration

    Runtime configuration (php.ini), extensions and the CLI.

Each section links to the official page. Titles and summaries by Extra Credit; the docs belong to their authors.

Source: endoflife.date