StaticIP, as the name suggests, is static in nature and never changes. If you're running a dynamic cloud environment, static IP is required to advertise your content/data to the internet.
A static IP is useful for various reasons. In cloud computing, a static IP address is advantageous for DNS queries. If IPs are changing, this can affect the content loading process.
Static IP addresses are IPs which do not change. They are common for business and cloud computing, which is why AWS includes this within the Elastic IP framework.