If you are like me and you prefer to always carry your entire sheet music library with you, you need a tablet, a suitable app to view and manage sheet music (mostly in pdf) and some time to organize it.
As a piano teacher, I have lots of teaching literature. The tablet is therefore an indispensable tool when searching for music books or individual pieces.
Every tablet is suitable and there are apps for both Android and iOS.
Since I use an iPad myself with the excellent app forScore, I can of course recommend it to you without hesitation.
Here you will find a blog post where forScore is briefly introduced.