The Industry Foundation Classes (IFC) file format was developed by buildingSMART®. The format maintains standards to import and export BIM elements and their parameters between software platforms. In many ways, an IFC is like an intelligent version of a DXF.
The IFC Wiki defines IFC as:
The Industry Foundation Classes IFC specification is a neutral data format to describe, exchange and share information typically used within the building and facility management industry sector. IFC is the international standard for openBIM and registered with the International Standardization Organization ISO as ISO16739.
The NBS defines IFC as:
IFC is an industry-wide open and neutral data format that is fast becoming the de-facto standard for rich data exchange.
IFC is clearly defined on Wikipedia as well:
It is a platform neutral, open file format specification that is not controlled by a single vendor or group of vendors. It is an object-based file format with a data model developed by buildingSMART (formerly the International Alliance for Interoperability, IAI) to facilitate interoperability in the architecture, engineering and construction(AEC) industry, and is a commonly used collaboration format in Building information modeling (BIM) based projects.