Semantics and Microformats
From Social Patterns
Any piece of information derives its value from the context in which it is presented or used. For instance, a collection of email ids may be useless to someone unless these are tagged as emergency contacts, or employees, competitors and so on. It is very often the 'data' about the 'data' - also called as 'metadata' - that gives information its context and makes it useful in a given situation. This meaning in the written word is what we refer to as semantics.
Microformats enable us to attach extra meaning to the information published on a web page by tagging existing XHTML markup with metadata. At their very core, Microformats are xhtml patterns you can use to describe the information in a given system, or a web page, in a manner that it is easily identifiable and shareable across the boundaries of the system without losing its context. Microformats preserve semantic relationships even when they are ported from one system to another and therefore are linked to the concept of data portability.