Isolation is being cut off from human interaction. Being alone is not being close to other people, even though they might be in the room. At least one of these are necessary for loneliness but not sufficient. I am often isolated or alone and the closest I can come to a definition of loneliness is a longing for antithesis. For me to know I exist, and know who I am, there must be something that identifies my limit. Knowing where I begin is also knowing where I end, and other people can provide this through validation or opposition.