| BArchivable | Interface for objects that can be archived into a BMessage |
| BAutolock | Convenient utility to make parts of your code thread-safe easily |
| BBlockCache | A class that creates and maintains a pool of memory blocks |
| BBufferIO | A buffered adapter for BPositionIO objects |
| BDataIO | Abstract interface for objects that provide read and write access to data |
| BFlattenable | Interface for classes that can flatten and unflatten themselves to a stream of bytes |
| BHandler | Handles messages that are passed on by a BLooper |
| BList | An ordered container that is designed to hold generic void * objects |
| BLocker | Semaphore-type class for thread safety |
| BMallocIO | A BPositionIO derived class that creates a memory buffer |
| BMemoryIO | A BPositionIO derived class that works on memory buffers |
| BMessage | A container that can be send and received using the Haiku messaging subsystem |
| BMessageFilter | Describes a message filter for BLooper and BHandler |
| BMidiConsumer | Receives MIDI events from a producer |
| BMidiEndpoint | Base class for all MIDI endpoints |
| BMidiLocalConsumer | A consumer endpoint that is created by your own application |
| BMidiLocalProducer | A producer endpoint that is created by your own application |
| BMidiProducer | Streams MIDI events to connected consumers |
| BMidiRoster | Interface to the system-wide Midi Roster |
| BPositionIO | Abstract interface that provides advanced read, write and seek access to data |
| BStopWatch | A timer class |
| BString | String class supporting common string operations |
| file_io_vec | Structure that describes the io vector of a file |
| file_system_module_info | Kernel module interface for file systems |
| usb_configuration_info | Container for a specific configuration descriptor of a device |
| usb_endpoint_info | Container for endpoint descriptors and their Haiku USB stack identifiers |
| usb_interface_info | Container for interface descriptors and their Haiku USB stack identifiers |
| usb_interface_list | List of interfaces available to a configuration |
| usb_iso_packet_descriptor | The descriptor for data packets of isochronous transfers |
| usb_module_info | Interface for drivers to interact with Haiku's USB stack |
| usb_notify_hooks | Hooks that the USB stack can callback in case of events |
| usb_support_descriptor | Description of device descriptor that the driver can handle |