A static IP address is called static because it does not change.
The public IP address assigned to the routers of most home and business users is a dynamic IP address. Larger companies usually do not connect to the Internet via dynamic IP addresses and instead have static IP addresses assigned to them which do not change.
In a local network like in your home or place of business, where you use a private IP address, most devices are probably configured for DHCP and thus use dynamic IP addresses. However, if DHCP is not enabled and you've configured your own network information, you're using a static IP address.