As shown on the stage at E3... the official E3 2017 Destiny 2 trailer. Allow me to reacquaint you with Ghaul.
Preorders get early access to the open Beta, launching on July 18 (for PS4 users) and July 19 (for Xbox users). If you don't preorder, you'll get access on the 21st. Full details, including PC dates, can be found at Bungie.net.