Kepler-11 is a Sun-like G-type star (about 0.96 solar masses, 5,663 K, 1.06 solar radii), 646 light-years from Earth. Kepler-11 was the first compact six-planet system, six low-density worlds packed inside Venus's orbit and continually perturbing one another. The system hosts 6 confirmed planets on orbits ranging from 10.3 days to 118 days. With 6 confirmed worlds, Kepler-11 is a densely packed system whose resonances, spacing, and formation history are active research topics. Mutual gravitational tugs between the planets can slowly reshape their orbits, preserving clues to the system's assembly. Kepler-11 b orbits well inside Earth's distance from the Sun. At 1.8 Earth radii, Kepler-11 b is a compact world comparable in size to rocky planets in our Solar System.