Redshift is an open-source screen color temperature adjustment tool that automatically adjusts screen temperature based on time, reducing blue light stimulation to protect eyesight. It can be easily installed on Ubuntu with a command. Redshift works by adjusting screen temperature according to geolocation and time, with smooth transitions. Users can run Redshift via command line or configuration file, setting parameters like latitude, longitude, and temperature values for day and night. This tool helps protect eyes by reducing screen glare and blue light exposure.