It wrapped media objects into compatible OLE 1.0 objects for insertion into OLE containers (example: office documents, presentations etc). It was a component of OLE before later versions and before OLE became ActiveX, and learned to embed stuff by themselves. https://en.wikipedia.org/wiki/Object_Linking_and_Embedding#O...
It's weird to think how big a part of desktop computing this once was, and now there's no real expectation for it. Web content's also not particularly embeddable. I used to love KParts in KDE - I'd start the morning with Konqueror open with some tabs showing web pages, some tabs showing my Excel time sheet or the Word docs with specs for what I was working on, and it was just totally normal that all this stuff worked and composed together.
