While on vacation last week, I read the book, The Tipping Point: How Little Things Can Make a Big Difference, by Malcolm Gladwell (it was in the cruise ship's library!).

Because I have wanted to read this book since it came out, I have previously mentioned it to a number of people, many of whom had already read it and told me: "you NEED to read it". They were right! I really liked this book and highly recommend it.

Gladwell uses models that show how epidemics are successful, and applies those models to areas like social change, childhood development and product marketing. Early on he says (paraphrased): contagiousness is a property of all kinds of things.

So, I have been thinking about the Internet, and specifically email, websites, blogging, RSS-type feeds and iCites in terms of contagiousness.

Obviously, at some point, something about the Internet became contagious and it moved from being a technical tool used by tens of thousands of techies / academics to a medium used by hundreds of millions of people from many walks of life. And, the web browser and websites were certainly a context in which that tipping point was passed.

I have been thinking about what has been contagious about the Internet, and I think addressibility is a key property, and the ability to interact with addresses is a key method of the Internet's contagiousness.

For example, this web page includes addresses to other web pages. Those addresses appear as hypertext links that you can click. You maybe came to this page through its address appearing on another website, in your browser bookmarks, in a summary in your RSS reader, or in an email message.

Email is contagious in one sense that everyone to whom you send a message gets your email address. The "reply" and "forward" buttons in your email client make each message a potential carrier of email addresses.

Email, I think, is the original contagious agent of the Internet, because each individual having an email address works to get others to get their own email addresses as well. We have seen, and we will probably see even more with the AOL Journals coming out next month, a similar contagiousness with blogs.

But, most people don't have blogs (i.e., website URLs) the way they have email addresses. Email requires a sender (author) and recipient (reader), whereas a blog generally just requires a sender (author).

If you have a blog, you don't need others to have blogs. If you have an email address, you do need others to have email addresses. I think this kind of requirement might be an essential feature for any online identity scheme to become pervasive. (See also Don Park's post on Three Volts about Voltage Security's identity-based encryption scheme.)

What is contagious about web pages, and many blogs exemplify this, is that they essentially advertise with each link: "your URL could be here". Websites are salesmen for creating websites—more specifically, website URIs lead to more website URIs. This is contagious, but less in the person-to-person manner of email.

Moblogging and photoblogging, I think, might emphasize the n-way potential of blogging that is like email: I show you / tell you what is up with me (on my blog) and you show me / tell me what is up with you (on your blog). Using websites this way more requires an author (sender) and reader (receiver) like email.

In my earlier post on The future of website interactions, I was talking about buttons for subscribing to RSS feeds and "Blog this" buttons. I think the goal of these is a contagiousness of online content. In other words, the content spreads from site to site, or from site to reader or some other application.

(With regards to quickSub that I mentioned in this post, by trying to include all the major feed reader / aggregator interfaces, I think it attempts to break-down one barrier to the spread of the feed-subscription epidemic.)

In this context of the spread of content online, the spread from site to site is through its addressibility, but a more elaborate interaction with addresses is evolving. This interaction is all along the lines of the grabbing of content from one site and adding it to another.

The minimal content being spread around is the content's address, and this interaction is like bookmarking (or blogrolling). But, the maximal content being spread around is inclusive of addresses, data and metadata. For example, this blog's full content RSS feeds include addresses, blog post content, and some blog post metadata.

The semantic web, as in XML and RDF, suggests that more and more metadata will be made accessible online, but I don't think the semantic web in itself extends the contagious addressibility of the existing web and email. So, I don't think there is going to be an epidemic of semantic websites sparked by the features of XML and/or RDF.

But, contagious content—the sharing of content from one site to another, can include XML and/or RDF and also can potentially capitalize on it.

With the iCite net, one of the visions for it is a kind of world of ends database with no assumption of clients that can't be servers or remote data that can't be as accessible as local data or of users who do not help define the meaning / value of information.

iCites aren't semantic websites as much as interfaces for the contagious sharing of content that, from one view, can be seen together as semantic websites. This sharing of content is simultaneously (part of) its definition of meaning and/or value.

the iCite net may become like a network of contagious databases where each addition of content simultaneously spreads new views of itself and of existing content. Each piece of new content should further enable the sharing of content from one site to another.