If there is just one way to define a blog, I would do it thus: a series of chronologically arranged journal entries available online alongwith several sourced hyperlinks. In terms of type, this one definition does it well. In terms of degree though, if there are to be more definitions than one, which I am sure is the compelling case: there are plenty. And it is amidst this scope of plenty, that some journalists seek their most preferred explanation.
Needless to say, I have found one which is as varied in degrees as possible, to include comments, pictures, external hyperlinks, and poems ranging from mine to Woody Guthrie’s.