Redshift is an open-source screen color temperature adjustment tool that automatically adjusts the screen temperature based on time to reduce blue light stimulation and help protect vision. It operates by automatically adjusting the screen temperature according to geographical location and time, with higher color temperature during the day and lower at night. Redshift can be easily installed on Ubuntu and offers two methods for configuration: command line execution or through a configuration file. Users can manually set parameters such as latitude, longitude, and color temperature to smoothly transition between different settings.