The plugins_url function is one of the many functions that can be used in plugins to help find the location of files in a WordPress installation. Other useful functions include:

• get_theme_root(): Returns the address of the theme installation directory
• get_template_directory_uri(): Retrieves the URI to the current theme's files
• admin_url(): Provides the address of the WordPress administrative pages
• content_url(): Indicates where the wp-content directory can be found
• site_url() and home_url(): Returns the site address
• includes_url(): Provides the location of WordPress include files
• wp_upload_dir(): Indicates the directory where user-uploaded files are stored