What am I?

I am fictional, I am factual,
I am there for you when you are bored,
I am for children, I am for adults,
I can take you all over the world.

I contain pictures, I contain writing,
I hold all the knowledge in the world,
I can be long, I can be short,
In me you see a story unfold.

I can be new, I can be old,
I am usually quite easy to carry,
I can be fun, I can be dull,
You will find me in a library.