Short answer
Dynamic IP is enough for most people. Static IP is mainly needed when a service must be reachable at the same address all the time.
Dynamic IP is most common
Most home connections use dynamic IP. The provider automatically assigns an available address. It may stay the same for a long time, but it is not guaranteed to be permanent.
Static IP for servers and remote access
Fixed IP is useful when you run a server, need VPN access to an office, use firewall rules for a fixed address, or want to avoid DNS updates when an address changes.
Alternatives to static IP
Dynamic DNS is often enough if you only need to find your home router. For companies, a static IP is often easier to document and secure.
Common questions
Is static IP faster?
No. Speed depends on the connection and provider, not whether the address is static.
Is static IP less private?
It can be easier to recognize over time because the address does not change.