Composer
Composer is the dependency manager for PHP.
It lets a project declare which libraries it depends on, then resolves, installs, and updates those dependencies in a structured way.
What it does
Composer manages project dependencies for PHP codebases.
It is commonly used to:
- Declare PHP library dependencies
- Install or update packages
- Generate autoloading configuration
- Standardize dependency versions inside a project
- Support package-based workflows in PHP and WordPress development
Core concepts
Dependency manager
Composer is not primarily a general system package manager.
It works on a per-project basis, usually installing dependencies into the project itself.
composer.json
Composer projects are typically driven by a composer.json file.
That file defines dependencies and other package metadata used to resolve and manage the project.
PHP ecosystem standard
Composer is the standard dependency-management tool in the PHP ecosystem.
That is why it appears in modern PHP frameworks, libraries, and more advanced WordPress workflows.
Common use cases
- Installing PHP libraries
- Managing framework dependencies
- Updating project packages
- Loading dependencies through autoloading
- Handling plugin and library workflows in PHP-based projects
Practical notes
- Composer is to PHP roughly what npm is to the JavaScript ecosystem, though the ecosystems differ.
- It is commonly used from a CLI and repo-based workflow.
- Composer can be used in WordPress projects, but the exact setup varies by team and hosting environment.
- Understanding Composer is important for modern PHP dependency and library management.
Sources Used
Frequently Asked Questions
Is Composer a package manager?
More precisely, it is a dependency manager for PHP.
Does Composer install packages globally?
Usually it works on a per-project basis, though it also supports a global project for convenience.
Is Composer only for frameworks?
No. It is also used for libraries, tools, applications, and many PHP-based project types.