Each Tweet contains 31 different data fields

"Consider the tweet. It’s short—140 characters and done—but hardly simple. If you open one up and look inside, you’ll see a remarkable clockwork, with 31 publicly documented data fields. Why do these tweets, typically born of a stray impulse, need to carry all this data with them?
While a tweet thrives in its timeline, among the other tweets, it’s also designed to stand on its own, forever. Any tweet might show up embedded inside a million different websites. It may be called up and re-displayed years after posting. For all their supposed ephemerality, tweets have real staying power.
Once born, they’re alone and must find their own way to the world, like a just-hatched sea turtle crawling to the surf. Luckily they have all of the information they need in order to make it: A tweet knows the identity of its creator, whether bot or human, as well as the location from which it originated, the date and time it went out, and dozens of other little things—so that wherever it finds itself, the tweet can be reconstituted. Millennia from now an intelligence coming across a single tweet could, like an archaeologist pondering a chunk of ancient skull, deduce an entire culture."
Source:  BusinessWeek, 7th November 2013