  We establish fundamental properties of infinite geodesics and competition
interfaces in the directed landscape. We construct infinite geodesics in the
directed landscape, establish their uniqueness and coalescence, and define
Busemann functions. We then define competition interfaces in the directed
landscape. We prove the second class particle in tasep converges under KPZ
scaling to a competition interface. Under suitable conditions, we show the
competition interface has an asymptotic direction, analogous to the speed of a
second class particle, and determine its law. Moreover, we prove the
competition interface has an absolutely continuous law on compact sets with
respect to infinite geodesics.
