History of Earth

Earth is the homeworld of humanity and the location of the Last City, the Traveler and the Guardians' Tower. Destinypedia calls it "the cradle of humanity"; most of its surface lies in ruins after the Collapse, with the Fallen, Hive, Cabal, Vex and Taken all contesting it. In Destiny 2 it contains several destinations:

• Cosmodrome: ruins of the Old Russian spaceport, the free-to-play starting area. Wikipedia notes it returned as a patrol location in Seasons 12-13 and became the setting of the new player experience introduced with Destiny 2: Beyond Light (November 2020).
• European Dead Zone: the main Year One Earth destination, home to The Farm and the Emerald Coast Gambit map.
• European Aerial Zone: a floating training island of lifted EDZ terrain, seen during Solstice.
• The Last City: humanity's last city beneath the Traveler, with the Tower atop the Wall.

Destinypedia also lists Felwinter Peak (the Iron Temple area), the Manhattan Nuclear Zone and ruins across other continents as Earth locations; the Destiny 1 Plaguelands patrol zone was added to Earth in Rise of Iron (September 2016, per Wikipedia).

How to get there

Select Earth destinations from the Director in orbit; the Last City and Tower are the default social hub. The Cosmodrome is available to all players.

Activities

Strikes, Lost Sectors, public events and patrols in the Cosmodrome and EDZ; Foothold is the Earth Battleground in the Cosmodrome.

Lore

Before the Collapse Earth suffered overpopulation; Destinypedia notes the planet's dark matter streams are theorized to have birthed the The Nine. Earth is where the Red War was fought: the Cabal Red Legion under Dominus Ghaul attacked the Last City and the Guardians retook it. The Dreadnaught returned to darken Earth's skies in Episode: Heresy.