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Understanding PHP

PHP works where nobody looks: on the server. Here we explain the language, its terms and typical misconceptions — without prior knowledge, but with enough depth for you to put technical answers into context.

Recommended reading order

  1. What is PHP and what is it used for?Start here: browser, server and what PHP actually does during a request.
  2. PHP in the backend: what happens after a form is submitted?The six steps every input goes through — and the error case.
  3. PHP and JavaScript: which tasks does each handle?The boundary between browser and server, where many project errors are decided.
  4. Variables, data types and arraysFrom here it gets concrete: the building blocks that all PHP code works with.
  5. Functions and classes in PHPHow building blocks become something reusable.
  6. What is object-oriented programming?The idea behind classes — and where it reaches its limits.
  7. Namespaces and autoloadingHow many classes coexist without name conflicts.
  8. ComposerThe tool that manages third-party code and finds the classes.

All articles in this section

What is PHP and what is it used for?Browser and server, the path of a request, areas of use and limits.Basics · about 6 minutes
PHP in the backendWhat happens on the server after a form is submitted.Basics to intermediate · about 7 minutes
PHP and JavaScriptWhich task belongs where and which errors arise from mixing them up.Basics · about 5 minutes
Variables, data types and arraysWith runnable examples and three comparison pitfalls that cause real bugs.Basics · about 7 minutes
Functions and classes in PHPHow repeated code becomes a building block — and when it becomes a class.Basics to intermediate · about 8 minutes
What is object-oriented programming?Objects, encapsulation, interfaces and the limits of inheritance.Basics · about 8 minutes
Namespaces and autoloadingWhy two classes may bear the same name and how PHP finds the file.Intermediate · about 6 minutes
ComposerManaging dependencies, and why install and update are different commands.Intermediate · about 7 minutes

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