WebMonkey writes on Metadata, Mark II:

So having a metadata-rich Web wouldn’t just improve our user experience as we search and surf the Web, but it would also augment the ability for "robots" or software agents to collect and process information on our behalf.

When people talk about the "Semantic" Web adding meaning to the Web, it’s not really for you and me — you and I generally understand whatever we're reading, and know which links we need to click to get certain tasks done — it’s about adding meaning that machines can process and navigate.

...via elearningpost