When conducting the IPS unit root test, the options that you can add to the command include "trend", "demean" and "lags".

What do these options actually mean and how does one understand when to select or not select each one? I have researched online and also used the help option in stata to try to understand, but I am still confused/unsure of when to use them.

Each option can alter the result of the test and change the outcome (ie whether or not there is unit root).