To put it in ridicolously simple words, semantics is about the meaning of something, what's actually in it. For geeks: Semantics is like the & operator in C. For everyone else, consult Wikipedia:Semantics.

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The Semantic Chat

Applying some thoughts from the semantic web folks to chat and the social network.

Melvin Carvalho mentions TimBL's http://www.w3.org/DesignIssues/LinkedData.html

  1. Use URIs as names for things
  2. Use HTTP URIs so that people can look up those names.
  3. When someone looks up a URI, provide useful information, using the standards (RDF, SPARQL)
  4. Include links to other URIs. so that they can discover more things.

> However, I'd struggle to see something scaling with the Web if it ignores linked data principles

It does follow those principles, but it uses a different transport. 

1. People and things have URIs like psyc://cepheide.org/~hellekin
   The psyc: however implies there may be a friendship/trust relationship
   or not, resulting in a different view of this URI depending on who you
   are. That is something people do not _expect_ from an http: URI and
   that http: needs extra data in order to provide.

2a. The psyced server also provides HTTP so it lets you have a quick
   look at me by using the same URI with http: in front
   (http://cepheide.org:4484/~hellekin - Hellekin changed the http port
   number though). But the information who YOU are and why YOU should
   see my phone number etc is lost. http: URIs would be misleading as
   people would think what they got is all there is.

2b. But a browser extension like psyczilla teaches the browser to browse
   psyc: rather than to use http: for people. A profile via psyc: looks
   just like the web in Firefox, but you actually get the data that has
   been made accessible specifically to YOU. A psyc: URI also implies
   you can subscribe to it and have it send things to you.

2c. PSYC could even be taught to route http URIs if that really is useful.

3. psyced outputs a web profile. It could use richer formats, but the
   richest format is the interactive data approach used via the PSYC
   protocol, so accessing the person/resource via psyc: automatically
   is a rich data operation.

4. Those profiles include links to groups, friends and microblogging.
   They could provide the richness of Facebook and beyond, but always
   taking in consideration who the viewer is. This is something you
   can't easily do with http: in a decentralized fashion. Are you going
   to give your credentials to every HTTP offering out there just in
   case they have some extra information tailored for you? Does every
   click you make require you to provide OpenID information? The user
   needs to be made aware that by clicking on a URI she is going to
   show who she is in order to get useful reply - having a different
   protocol URI delivers that understanding: You are clicking on something
   new - don't expect it to behave like the old. And psyc: URIs only
   start working after you logged into your own PSYC identity.

It scales with the web, since PSYC is just as decentralized as HTTP. In fact it adds the concept of one-to-many distribution of data that HTTP is lacking, so it doesn't need to be hosted on a "cloud" in order to deliver one source's data to millions of interested peers. One of the reasons amazing applications end up in big silos on the web is because HTTP isn't rich enough to decentralize them natively, or it isn't being used in a rich enough way. So everyone puts extensions on top that only work with their own domain and server.