The external limiting membrane (ELM) is a structural feature of the retina that separates the outer nuclear layer from the inner segment of the photoreceptor cells. Also known as the outer limiting membrane, this layer is composed of specialized cells which provide mechanical support and a barrier against the ingress of fluids and other substances. Synonyms for the ELM include the apical junctional complex, the Zonula Occludens, and the tight junctions. These structures all play a role in maintaining the integrity of the ELM and contribute to the normal functioning of the retina. Understanding the different terms used to describe the ELM can help facilitate communication and collaboration among healthcare providers and researchers working in the field of ophthalmology.