| Adapter |
| Auth |
| AdapterInterface |
| CookieCollection | Container class for cookies used in Http\Client. |
| FormData | Provides an interface for building multipart/form-encoded message bodies. |
| FormDataPart | Contains the data and behavior for a single part in a Multipart FormData request body. |
| Message | Base class for other HTTP requests/responses |
| Request | Implements methods for HTTP requests. |
| Response | Implements methods for HTTP responses. |