What is a blogging "platform"? For that matter, what exactly does "blogging" consist of? Many answers below don't provide what I would call a platform - many

What is a blogging "platform"? For that matter, what exactly does "blogging" consist of? Many answers below don't provide what I would call a platform - many aspects of what one might call "bloggin" have not been thought through (e.g. archiving and exporting of entries and comments, how are comments integrated, security features, hosting...) These are all part of the design of a platform. Whatever you think of it, Wordpress is certainly a platform. Many of the answers (e.g. jekyll, rolling your own...) are not. It would be good to actually define "blogging" and "blogging platform", which I think would be somewhat difficult to do.