A way of notating music and sound visually but without using traditional notation. Traditional notation provides a performer with instructions about the type of sound that they should create. When we record sounds we no longer need a performer to follow our instructions, we can work directly with the sound. In order to visualise what is going on in the sound we can look at the sounds waveform or its spectrogram. However, these will only provide us with scientific descriptions of the sound energy which might be quite different from what we actually hear.
If we want to understand the sounds that we hear, and relationships between the sounds, we can draw shapes and textures to represent what it is that we hear. Because sounds have both shape (envelope) and texture (timbre) it is possible to draw them visually. A graphic score is a visual interpretation of a piece of music. It could be in black and white (focussing on shading and shape), or in colour. Any shapes or textures can be used, so long as you are able to consistently link the sound with the image.
Most graphic scores will have a timeline running horizontally, and tend to provide a rough indication of pitch through vertical arrangements.