The semantic web
If you read more about triple-stores, you may get sucked into a maelstrom of articles written about the semantic web. The triple-store data model is completely independent of the semantic web—for example, Datomic  is a triple-store that does not claim to have anything to do with it. But since the two are so closely linked in many people’s minds, we should discuss them briefly.
The semantic web is fundamentally a simple and reasonable idea: websites already publish information as text and pictures for humans to read, so why don’t they also publish information as machine-readable data for computers to read? The Resource Description Framework (RDF)  was intended as a mechanism for different websites to publish data in a consistent format, allowing data from different websites to be automatically combined into a web of data—a kind of internet-wide “database of everything.”
Unfortunately, the semantic web was overhyped in the early 2000s but so far hasn’t shown any sign of being realized in practice, which has made many people cynical about it. It has also suffered from a dizzying plethora of acronyms, overly complex standards proposals, and hubris.
However, if you look past those failings, there is also a lot of good work that has come out of the semantic web project. Triples can be a good internal data model for applications, even if you have no interest in publishing RDF data on the semantic web.
-  Technically, Datomic uses 5-tuples rather than triples; the two additional fields are metadata for version-tag.