In a NASA 360 video University of California Santa Barbara professor Philip Lubin describes the process of "photonic propulsion." It involves propelling objects with mass-free particles of light (photons). Basically, pushing spaceships with a great, big laser.
That speed is totally unheard of as far as human technology goes. And at a relatively reasonable energy cost, it sounds too good to be true. So what's the catch? According to Lubin there doesn't appear to be one. At least none that we couldn't overcome.
"There is no known reason why we could not do this," Lubin says in the video.
Lubin has a far more detailed roadmap on the subject, if you're interested in the specifics. Though the broad benefit is this: at that speed we could scout, and perhaps one day reach potentially habitable exoplanets light years away from Earth.