PDF history and something special from Adobe

Part One: PDF history 

PDF is a formal open standard, ISO 32000. It was invented by Adobe Systems 17 years ago.

PDF = Portable Document Format

History of the PDF by Adobe Systems

The image links to a pleasant interactive timeline of Adobe Systems and its role in the development of the PDF. The chronology is in Flash, and thankfully free of any video or audio. Read more about Adobe Systems role in the history of PDF file development.

PDF files are more versatile than I realized, and

• are viewable and printable on Windows®, Mac OS, and mobile platforms e.g. Android™
• can be digitally signed
• preserve source file information — text, drawings, video, 3D, maps, full-color graphics, photos — regardless of the application used to create them

Additional PDF file types exist, including PDF/A, PDF/E and U3D. All are supported by Adobe software. 

Twitter Influence System

Twitter influence is subtle and difficult to capture

Twitter influence ranges beyond measuring followers, @ replies and re-tweets. It isn’t trivial to calculate the true reach of an individual’s Twitter updates. Such are the challenges encountered in quantifying influence (perhaps even value) of Twitter users’ activity.

Actual percentage of Twitter content read

This chart shows the percentage of tweets read in relation to the number of people followed. As could be expected, the more people you follow, the smaller the percentage of tweets you actually read.

Both images, Twitter Influence EcoSystem and Percentage of Tweets Read are original work by John V Lane, via Flickr, and reproduced here under Creative Commons License/by-sa/2.0.