In situ measurements of the solar wind have been available for almost 60 years, and in that time plasma physics simulation capabilities have commenced and ground‐based solar observations have expanded into space‐based solar observations. These observations and simulations have yielded an increasingly improved knowledge of fundamental physics and have delivered a remarkable understanding of the solar wind and its complexity. Yet there are longstanding major unsolved questions. Synthesizing inputs from the solar wind research community, nine outstanding questions of solar wind physics are developed and discussed in this commentary. These involve questions about the formation of the solar wind, about the inherent properties of the solar wind (and what the properties say about its formation), and about the evolution of the solar wind. The questions focus on (1) origin locations on the Sun, (2) plasma release, (3) acceleration, (4) heavy‐ion abundances and charge states, (5) magnetic structure, (6) Alfven waves, (7) turbulence, (8) distribution‐function evolution, and (9) energetic‐particle transport. On these nine questions we offer suggestions for future progress, forward looking on what is likely to be accomplished in near future with data from Parker Solar Probe, from Solar Orbiter, from the Daniel K. Inouye Solar Telescope (DKIST), and from Polarimeter to Unify the Corona and Heliosphere (PUNCH). Calls are made for improved measurements, for higher‐resolution simulations, and for advances in plasma physics theory. Plain Language Summary The Sun's atmosphere, called the solar corona, is a very hot plasma (ions and electrons) that reaches temperatures of 1000000 K or more. The coronal plasma continually expands away from the Sun, carrying solar magnetic field with it. This is the solar wind. It reaches speeds of hundreds of kilometers per second and fills the solar system. The space carved out by the solar wind flow defines the heliosphere. The formation of the solar wind and its evolution as it flows away from the Sun is fundamental to how the Sun and stars get rid of stressed magnetic fields and involves physical processes that operate throughout the universe. Additionally, the solar wind constantly bombards Earth's magnetic field and plasma environment, driving dynamics called space weather. The solar wind is the medium through which larger space weather events from solar storms propagate. Understanding the solar wind is therefore key for understanding the space environment around Earth. In this paper, we synthesize input from the heliophysics community on the outstanding questions of solar wind physics. We describe the current state of research, an updated framework for understanding solar wind formation, and future needs and opportunities for progress, including what is likely to be accomplished in near future with data from Parker Solar Probe, from Solar Orbiter, from the Daniel K. Inouye Solar Telescope (DKIST), and from Polarimeter to Unify the Corona and Heliosphere (PUNCH). Key Points Nine outstanding questions of solar wind physics are synthesized from inputs from the heliospheric research community New ways of viewing these questions are put forth, and suggestions for future progress are offered Calls are made for improved measurements, simulations, and plasma physics theory