This is an Arduino library for the SHT21 and SHT25 humidity and temperature sensors.
To download. click the DOWNLOADS button in the top right corner, rename the uncompressed folder SHT2x. Check that the SHT2x folder contains SHT2x.cpp and SHT2x.h
Place the SHT2x library folder your <arduinosketchfolder>/libraries/ folder. You may need to create the libraries subfolder if its your first library. Restart the IDE.