An Editor ID (sometimes called a GECK ID) is a text identifier used to reference objects. It functions similarly to a Form ID, although it is not limited to 8 characters and a hexadecimal character set.
Editor IDs function more similarly to the Form ID of an object, in that it remains unchanged for all references of that object. The Editor ID serves as a more human-readable identifier and is often very similar to the names of the NPCs, items, etc. that it is associated with.