What are some common techniques for handling language localization in PHP web development projects?

When handling language localization in PHP web development projects, a common technique is to use language files that contain translations for different languages. These language files can be stored in a directory and loaded dynamically based on the user's language preference. By using PHP's built-in functions like `gettext()` or custom functions to retrieve the translated strings, developers can easily implement multilingual support in their web applications.

// Set the language based on user preference or default to English
$language = isset($_SESSION['language']) ? $_SESSION['language'] : 'en';

// Load the appropriate language file
$language_file = "languages/{$language}.mo";
putenv("LC_ALL={$language}");
setlocale(LC_ALL, $language);
bindtextdomain($language, 'path/to/language/files');
textdomain($language);
bind_textdomain_codeset($language, 'UTF-8');

// Retrieve translated strings using gettext()
echo gettext("Hello, world!");