Focus peaking is an extremely useful tool built into modern Olympus MFT and advanced compact cameras.
Basically, focus peaking allows you to see which areas are sharply in focus in the photo, in live time, by highlighting the in focus areas a bit like how underexposed and over-exposed are shown to you by the camera flashing them up.
It's ideal for use when using manual focus, especially when doing macro work, as it will allow you to work smoothly and quickly, revealing to you which areas are sharp, something which can be tricky to tell when photographing smaller subjects.
To learn more about the Focus Peaking abilities of the Olympus OM-D E-M1, take a look at Damian Mcgillicuddy's video, showing it in action.
The video can be found below, plus more video tutorials can be found on the BigDogsTopTips YouTube channel.