Around 400,000 positron detections have been confirmed in this first batch of data - positrons that are of energies consistent with the signature of dark matter annihilation.
Dark matter is thought to make up 80 percent of all matter in the Universe, the rest is "baryonic matter" - i.e. the stuff we're made of. But the vast majority of matter is locked in an invisible component of matter. As the moniker suggests, dark matter is dark; it doesn't interact with electromagnetic radiation. However, dark matter still carries mass that has a gravitational effect on space-time and through indirect means we can detect its gravitational presence.
ANALYSIS: Dark Matter Matters - When You Can't Find It
Theory suggests that Weakly-Interacting Massive Particles (WIMPs) may be a part of non-baryonic matter, bulking up the mass of the Universe. WIMPs are their own anti-particles; when two WIMPs collide, they annihilate and produce positrons and electrons (and energy). But for physicists to confirm WIMP annihilation does occur, the positrons need to have a specific energy signature.