By default, an ec2 instance would not include a swap area and if you are running a micro-instance this can mean that you will quickly run out of memory since it comes with only 613MB of RAM. This would result in errors and at times crash your instance since it cannot find enough RAM to keep your programs running.
Adding a swap area is basically telling your operating system to use a part of your hard drive space as RAM. So when your primary memory is running full, it ‘swaps’ a part from the RAM to the hard drive, thus freeing up some memory for your program. So how do you know whether your computing instance is actually using a swap area or not.