Skeletons are the cheapest card that you can use in Clash Royale. They are low hit point swarm troops and melee ground targeting units. When Skeletons focus on one target, they can deal strong damage even against tanks like Giants. They can also be used to distract strong single target troops like Prince, Pekka and Skeleton Giant.
Even though the Skeletons might look weak because of its fragile hit points, when used correctly you can save much elixir spending against your opponents.