No not IVF, EVF for electronic viewfinder. Years ago with my Olympus EP2 I was glad there was one on a camera I bought mainly for holidays. It meant I could use the camera the way I am used to when taking portraits. At the time it was not that clear, didn’t refresh quickly and blacked out between shots making moving objects a challenge. Move forward to 2017 and the EVF is nearly as clear as an optical viewfinder, can track action shots ( the OMD-M1mk2 can shoot up to 60 frames a second ) and has an imperceptible blackout. These used to be my second cameras but now my traditional DSLRs sit on the shelf more and more.
The main reason reasons are that the image quality is excellent and creates comparable images while having the advantage in ambient light that what you see in the viewfinder is the shot the way it will be captured. This is incredibly useful in situations where the light is rapidly changing. Once you try it it’s hard to go back.