What is an echo in locke and key?

In the Locke and Key series, an echo refers to a type of supernatural entity that is created when someone dies a violent death. This entity is bound to the location of the death and continuously repeats the same actions, sounds, or words over and over again.

For example, in the first episode of the series, the character Sam Lesser kills their father, and an echo is created at the scene of the crime. This echo repeats the sound of a ringing phone, which was present at the time of the murder, over and over again.

The echoes in Locke and Key are dangerous, as they can cause harm to those who come into contact with them. They are also difficult to get rid of and require specific methods to break the cycle and release them. Throughout the series, the Locke family encounters several echoes and must find ways to deal with them.