IECore is a cross-platform library for Linux, Windows, and macOS that leverages ImGui as its user interface. It serves as the core framework for all Interactive Echoes (IE) applications, offering a plug-and-play setup with pre-configured entry points, making it simple to start developping C++ applications.

Before reading the GH page, I was going to say "wouldn't TridentCore be a more appropriate name?".

But I think IECore is a name that will be associated with MSIE before a 'Interactive Echoes'. A name change may be something to think about.

So it's not Internet Explorer core library for Linux, Windows and MacOS.