Formally defined Software Components (SWCs) with clearly specified interfaces to the Basic Software (BSW) form one set of elements of the AUTOSAR architecture. The modules of the BSW provide fundamental standard services such as bus communications, memory management, IO access, system and diagnostic services.

Another element of AUTOSAR is the runtime environment or RTE, which controls the connections between SWCs and from SWCs to the BSW.

The Virtual Functional Bus (VFB) specified by AUTOSAR represents the conceptual foundation for communication between SWCs and for the use of BSW services. Since the entire communication of SWCs is based on the VFB, the SWCs are independent of the ECU hardware. This supports reuse of SWCs across projects and platforms. The VFB is implemented for a specific vehicle by supplying a specifically configured RTE in conjunction with a suitably configured BSW for each ECU.