What is the difference between Swapon and Swapoff?

Could you please elaborate on the key differences between Swapon and Swapoff? I understand they are both related to virtual memory management, but I'm not clear on how they differ in their functionality and usage scenarios. Specifically, when would one use Swapon and when would Swapoff be more appropriate? Additionally, are there any potential consequences or considerations one should be aware of when switching between these two operations?