(Just a trial to depict the reality of today.)

I'm a regular device,
Available in different size.
Though my usual shape is rectangle,
Several firms did fold me in angles.

I'm a regular device,
Comprising of calenders and clocks;
Also have knowledge of stocks.
Some save future plans in my notes,
While some like to share quotes.

I'm a regular device,
Who stole calculator's job,
Still help track someone in a mob.
I shutted down many theatres,
Still people praise my...