Twilight Sparkle accidentally discovers that her Friendship Castle can allow her to magically connect to a vast interactive library in another dimension. At first blush, it appears to be full of open journals, So she jumps in, starts her own journal and fills in the gaps as to what it's like to live in Equestria. There's food, fun, friends, festivals, facts, footnotes, finds and information.

What could Twilight have to say
If she journaled every day
Would she bemoan the ponies she dissed?
Or would she just jot down her laundry list?
You'd find out, you would be in the know
if to Twilight's Blog you would go.

To clarify, this is in essence a series of interrelated stories in chronological order and told by Twilight, from her point of view. There is also world building mixed in, namely the mechanics of wielding magic, thoughts about pocket universes and How Equestria Was Made.