Solar sails are a new and innovative technology that can allow us to send spacecraft faster and farther than ever before. A solar sail works by the same principle as a normal sail on Earth: a normal sail gets hit by wind particles, and this impact creates enough force to move the sail and its vehicle forwards. A solar sail will reflect sunlight, using the constant pressure of the photons hitting the sail to propel itself. Because it is powered by solar energy, a solar sail can operate for extremely long amounts of time without stopping. Solar sails are finding many new roles to fill in upcoming projects from agencies such as NASA and the like, and they may play a pivotal part in space exploration in the future.
Sources: https://www.nasa.gov/launching-science-and-technology/solar-sail-test-will-study-near-earth-asteroid