Editing The Explorer's Handbook (section)

=== Sites ===

There are five kinds of exploration sites one might encounter while participating in exploration activities, these being mining sites, gas sites, combat sites, relic sites, and data sites. Mining and combat sites will often appear as anomalies without having to scan them down with a core probe launcher, and work very much like mining and combat anomalies in other aspects of the game. Gas sites operate like mining anomalies, save for that instead of ore or ice to mine, they have gas deposits that one can collect with gas scoops or gas harvesters. 

Relic and data sites are unique in that they require specialized analyzers fitted to your ship in order to interact with them. Both of them contain different cannisters one must access with the relevant analyzer module, which opens the hacking minigame. Once the minigame is complete, one can open the cannister to take the contents, which may be anything from an empty cache to tens of millions of ISK worth of scavenged materials.

The sixth 'site' you may encounter, wormholes, are not really a site at all, but more akin to a doorway. They can lead anywhere, from high sec space, to null sec, to the unknown depths of wormhole space. Be careful with these, they won't automatically be marked on your scanner on the other side, so we recommend bookmarking your exits so you can get back if need be.