Books Piano Pages   William Wieland
Books are primarily linear: Page 1 Right Arrow Page 2 Right Arrow Page 3 Right Arrow etc.
Web pages are scrolls which can be cut up like books: Piano Keys
Links make the Internet fundamentally nonlinear:

(Books can also be nonlinear, e.g. endnotes or
a table of contents, but links are easier to use.)
  Up Left ArrowUp ArrowUp Right Arrow
Left ArrowWeb
Page
Right Arrow
Down Left ArrowDown ArrowDown Right Arrow
"Piano Pages" occasionally use flow charts:

(You may bake a cake first or decorate first,
but you should do both before you have a party.
Please click on the links.)
  Decorate
Down Arrow
Bake a cake  Right Arrow  Have a party