For along time 1 has not been considered prime nor composite.
prime - A number which has two factors only, one and itself
composite - A number that has more than two factors
1 can be divided by 1 and itself, but no other number. This means that by definition it is prime, but logically it is neither. There is no term to describe a number that only had one factor. But also one could be composite. One can be divided by one, which is itself, but is also the only number that could create and endless loop, because 1x1x1x1... = 1. So there are two sides to the argument, event though 1 being prime is more rational.
If you come up with any theory's, I would love to know!