What is Outer darkness?

In Christianity, the "exterior darkness" or outer darkness is a place referred to three times in the Gospel of Matthew into which a person may be "cast out", and where there is "weeping and gnashing of teeth". Generally, the outer darkness is thought to be hell; however, many Christians associate the outer darkness more generally as a place of separation from God or from the metaphorical "wedding banquet" that Jesus is expected to have upon his Second Coming.