This paper introduces the LV2 Atom extension, a simple yet powerful data model designed for advanced control of audio plugins or other real-time applications. At the most basic level, an atom is a standard header followed by a sequence of bytes. A standard type model can be used for representing structured data which is meaningful across projects. Atoms are currently used by several projects for various applications including state persistence, time synchronisation, and network-transparent plugin control. Atoms are intended to form the basis of future standard protocols to increase the power of host:plugin, plugin:plugin, and UI:plugin interfaces.