| Name | Description |
|---|---|
| Archive | The **Archive** class is used to query cached analytics statistics (termed "archive data"). |
| AssetManager | AssetManager is the class used to manage the inclusion of UI assets: JavaScript and CSS files. |
| BaseFactory | Base class for all factory types. |
| Common | Contains helper methods used by both Piwik Core and the Piwik Tracking engine. |
| Config | Singleton that provides read & write access to Piwik's INI configuration. |
| DataTable | The primary data structure used to store analytics data in Piwik. |
| Date | Utility class that wraps date/time related PHP functions. Using this class can be easier than using `date`, `time`, `date_default_timezone_set`, etc. |
| DbHelper | |
| Filechecks | |
| Filesystem | Contains helper functions that deal with the filesystem. |
| FrontController | This singleton dispatches requests to the appropriate plugin Controller. |
| Http | Contains HTTP client related helper methods that can retrieve content from remote servers and optionally save to a local file. |
| IP | Contains IP address helper functions (for both IPv4 and IPv6). |
| Notification | Describes a UI notification. |
| PiwikTwigFilterExtension | |
| Plugin | Base class of all Plugin Descriptor classes. |
| ProxyHttp | Http helper: static file server proxy, with compression, caching, isHttps() helper. |
| ReportRenderer | A Report Renderer produces user friendly renderings of any given Piwik report. |
| Segment | Limits the set of visits Piwik uses when aggregating analytics data. |
| SettingsPiwik | Contains helper methods that can be used to get common Piwik settings. |
| SettingsServer | Contains helper methods that can be used to get information regarding the server, its settings and currently used PHP settings. |
| Site | Provides access to individual [site entity](/guides/persistence-and-the-mysql-backend#websites-aka-sites) data (including name, URL, etc.). |
| Twig | Twig class |
| UpdateCheck | Class to check if a newer version of Piwik is available |
| Updater | Load and execute all relevant, incremental update scripts for Piwik core and plugins, and bump the component version numbers for completed updates. |
| Updates | Abstract class for update scripts |
| UrlHelper | Contains less commonly needed URL helper methods. |
| Version | Piwik version information. |
| View | Encapsulates and manages a [Twig](http://twig.sensiolabs.org/) template. |