IPv4 addresses can be obtained from Internet Service Providers (ISPs) or from Regional Internet Registries (RIRs) such as the American Registry for Internet Numbers (ARIN), the Réseaux IP Européens Network Coordination Centre (RIPE NCC), and the Asia Pacific Network Information Centre (APNIC). However, it's important to note that the availability of IPv4 addresses is limited due to the depletion of the IPv4 address space. As a result, many organizations are now transitioning to IPv6, which offers a much larger address space.