Simple Definition:

EMF stands for electromagnetic field [a type of invisible energy created by electrically charged objects]. It consists of electric and magnetic fields that surround these objects. EMF has the ability to exert a force on charged particles [particles that have an electric charge, either positive or negative, such as electrons and protons]. This force can influence the movement and behavior of these particles, causing them to be attracted or repelled. Common sources of EMF include power lines, electrical appliances, and wireless devices such as cell phones and Wi-Fi routers.

For example, when you rub a balloon on your hair, it creates an electric charge on the surface of the balloon. This electric charge creates an EMF that can attract small pieces of paper towards the balloon.

Very Simple Definition:

EMF (Electromagnetic Field) is a special energy that can make things attract or repel [push away] each other.

For example, when you rub a balloon on your hair, there is an electromagnetic field on the balloon, and it can pull small pieces of paper towards it.