This site is called Regular Memory, and, although it may resemble a blog, it makes no claim to be such a thing. You might ask "well then what is it?". In response, I'd stay silent just long enough to undermine my eventual answer, and then I'd say "it's a blog". If you asked me what a blog is, I'm not certain I'd be able to tell you.
I think, fundamentally, it's important to accept that some things can only exist in a state of being undefined. To know if these undefined things have value, we must measure them in some way. A thought is a kind of measurement, and what is a thought, but a memory. In some sense, a blog is a set of memories; a set of measurements. Sometime after I failed to tell you what a blog is, and you walked away, a thought would occur to me; a blog is a set of measurements of a thing that is undefined.