What is an IFC file or model?
IFC (Industry Foundation Classes) is a data format for building information models. It is a data format just like for example Excel. What makes it special is, that it is a format especially for building information. As such it is most widely supported in the industry. Still, it is just a data format. It can be used for storing the building data, but mostly it is used in data exchange between different construction professionals and their applications.
IFC is open, meaning, that it is not controlled by any individual commercial entity. It is important to understand, that IFC is a standard for the format, but not for the content itself. To make the content consistent and rich you need Simplebim.