Frontier started out as a scripting environment for the Apple Macintosh. It could be used to automate OS-level activities (moving files around, etc.), and could send Apple Event-s to other applications. It was used a fair amount by people in publishing to push text files into page layout apps, process images for layout, etc.
It was beaten in the marketplace by Apple Script, which was free and pushed by Apple.
It then became a web scripting environment. [I used it at Medscape](http://webseitz.fluxent.com/articles/Bill Seitz Medscape And Frontier) when we started out running our web servers on Macs. I loved it.
Its focus shifted to web content management, and it became Userland Manila.
Then, a client version was developed for a variety of purposes. It was initially called Pike, then became Radio Userland.
It's always had a strong OutLining flavor. Scripts are written as outlines (not unlike Python, though Frontier has always had a more explicit outlining-style interface with everything). There has always been an integrated objectbase (I'm not sure it warrants the more formal label of Object Data Base) to store the base framework, custom scripts, and data (not unlike Zope).