Our brains are very clever at keeping us safe in difficult times. They can can give us help in the immediate moment of a difficult life event and protect us from feeling too distressed all the time afterwards. However this helpful mechanism can be counterproductive once the threat is in the past in not letting us process things to a point where they don't interfere with everyday life e.g. where we have flashbacks or are distressed by a trigger (such as smells, sounds or visual stimuli).
When we have had bad experiences our brains do not always neatly think these through and leave them behind. This technique helps our brains recall and link all relevant bits of the experience (some of which we have forgotten and some of which may be linked to other experiences) in a way that helps us remember in a less emotional way than before.
This technique requires minimal discussion of the content of past experiences so is suitable for where talking openly is more difficult, where recall is painful or where we don't have the words to explain. It uses eye movement, sound, pulsating buzzers, drumming or tapping gently to help with the joining up process of memories.
This can be a very quick and effective process compared to some other treatments. It is very effective where difficulties are holding you back from reaching your potential and/or where memories are repeatedly playing in your mind.
EMDR works well both in person (at a therapy room, face to face with a therapist) or online. So if you have limited time or have personal circumstances which makes it hard to access in person therapy, this can be a great, practical alternative.