A spot fleet is similar to a spot instance but instead of bidding for 1 instance you are bidding for multiple. You can set your max price and as long as you don’t go above that your instances will continue to run. Optionally, a spot fleet can also contain on-demand instances. When you create your spot fleet you have a few options, it can be capacity optimized which will give you your lowest risk of interruption and attempt to launch as many instances allowed or price capacity optimized which will give you the lowest priced spot instances within your available pools.