Redshift is an open-source screen color temperature adjustment tool that automatically adjusts the screen color temperature based on the time to reduce blue light stimulation and help protect eyesight. It supports manual latitude and longitude settings, smooth transitions to ensure gradual color temperature changes. Redshift can be easily installed on Ubuntu using the command "sudo apt-get install redshift" and run via command line or a configuration file. Users can customize daytime and nighttime color temperatures, enable smooth transitions, and manually set location details for optimal eye protection.