What does 4E stand for in shoes?

Could you please clarify what the acronym "4E" represents in the context of shoes? Is it referring to a specific size, width, or perhaps a brand identifier? It's not immediately apparent from the information provided, so I'm curious to know if there's a standard meaning for this abbreviation within the shoe industry. Additionally, if it does signify a size or fit, could you elaborate on how it compares to other sizing systems or what kind of footwear it's typically associated with?