Alternates
An alternate is another airport. It is not the parallel runway of your destination. The alternate should be sufficiently far away from your destination that if weather, e.g. fog, was a problem at the destination then your alternate may be alright. The fuel to get to the alternate is part of the flight plan calculation and I have never heard of anybody wanting to use their destination as their alternate! What would you do if your destination was closed and you didnt have fuel to go anywhere else. Nightmare.