
Forewor d
The 21st century started a major transformation in knowledge creation, stor-
age, and sharing. Gutenberg’s printing technology brought the era of text doc-
uments that dominated human knowledge dynamics for about six centuries.
Technology once again started transforming knowledge mechanisms. Mobile
phones and their cameras, good bandwidth, increased storage and processing
power are bringing a major unprecedented revolution in society. Photos and
videos have started becoming the new documents. Until the last century, doc-
uments were textual with the use of photos and figures to enhance them. Now
documents are becoming visual, with the use