Inspired by the visionary efforts of building Arecibo, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) was formally established as a stand-alone project in 2007. Through much trials and tribulation, FAST started normal operation in 2020 and has just finished its first internationally open call for proposal. I report here a few science highlights so far, particularly from the Commensal Radio Astronomy FAST Survey (CRAFTS: Li et al. 2018 IEEE MW). Enabled by a novel calibration technique, CRAFTS simultaneously records pulsar, Galactic HI, extra-galactic HI, and transient data streams, the first such commensal survey worldwide. CRAFTS has discovered more than 150 new pulsars, including at least one DNS system, 6 new FRBs including an active repeater that has been localized and with a colocated persistent radio source, discovered HI galaxies, started to produce high-quality HI images. Other dedicated programs have found first evidence for 3D alignment between pulsar spin and spatial velocity (Yao et al. 2021 Nature Astronomy), realized a new Zeeman tracer (Ching et al. under review for Nature), namely HI Narrow Self-Absorption (HINSA), constraining the cold gas content, particularly dark gas, through absorption (Tang et al. 2021 submitted), etc. Possibly the last giant single dish of its kind, FAST has the potential to further explore a unique parameter space of the cosmos and to keep producing significant discoveries in the coming decades.