The Parker Solar Probe (formerly Solar Probe+) will be a historic mission, flying into the Sun's atmosphere (or corona), for the first time. Coming closer to the Sun than any previous spacecraft, the Parker Solar Probe will employ a combination of in situ measurements and imaging to achieve the mission's primary scientific goal: to understand how the Sun's corona is heated and how the solar wind is accelerated. The Parker Solar Probe will revolutionize our knowledge of the physics of the origin and evolution of the solar wind.