Don't Panic: PHP Fundamentals

PHP is the server-side language that waits behind a web server, receives a request, does some work, and sends back HTML or JSON. The browser gets the finished result, not the PHP code. This arrangement has been serving the web since PHP began as a collection of CGI scripts in 1994, which is an impressively durable career for something that started by counting page visits.

The central idea is the request lifecycle. A browser asks, the web server passes the request to PHP, PHP runs from start to finish, and the server returns the output. Then the request's memory goes away. Each request starts with a blank slate, so anything that must outlive it belongs in a database, cache, session store, or queue. PHP is not forgetful; it is very disciplined about putting yesterday's paperwork in the shredder.

The first surprise is that dynamic typing does not mean modern PHP has no opinions about types. Variables remain flexible, but functions, return values, and class properties can carry declarations that the runtime enforces. PHP 8 also brings union types, enums, readonly properties, fibers, and other ways to describe program structure. These are not decorations for a code review. They make the shape of input and output visible where it matters.

A second useful landmark is Composer, the dependency manager. It records packages in composer.json, pins resolved versions in composer.lock, and generates an autoloader for classes. That removes a great deal of manual file inclusion, although it does not remove the need to test a real request or verify the environment. Composer organizes the library cupboard. It cannot tell whether somebody left the plumbing disconnected.

The ecosystem is broad enough to be confusing at first. Frameworks such as Laravel and Symfony add routing, templates, database access, and testing structure. WordPress, Drupal, and other content platforms place PHP inside larger publishing and commerce systems. PHP-FIG's PSRs, interoperability standards, help libraries cooperate. The language also carries older habits, so current PHP documentation is a safer guide than a tutorial with an impressive vintage.

Read the Intro when the request lifecycle and the language's limits need a fuller explanation. Use Slides for the map from browser to web server to PHP to response. Keep the Cheatsheet nearby for syntax, PDO prepared statements, Composer commands, and security details. The Practice Reference and exercise turn that map into a small running endpoint. Field Notes covers the operational traps that appear after the first successful request, which is when the paperwork begins to develop opinions.

Don't Panic: PHP Fundamentals

Relevant careers