Before continuing, learn why we need Network Address Translation (NAT), if you are new to the concept.
Static NAT is one-to-one mapping between Private IPv4 Addresses and Public IPv4 Addresses. Static NAT requires having one public IPv4 address for every Private IPv4 Addresses in inside network. Hence, IPv4 Address conservation is not possible using Static NAT. The main benefit of Static NAT is that Static NAT allows a computer from a remote network to initiate a connection to a Server in inside network, configured with a Private IPv4 Address.
Static NAT allows a Server from inside network (configured with a Private IPv4 Address), such as a Web Server or Mail Server, be reachable over the Internet.
Address translation concept of Static NAT and Dynamic NAT are similar. Both Static NAT and Dynamic NAT translate Source/Destination IPv4 Addresses. The difference is only that Static NAT is one-to-one translation and Dynamic NAT is many-to-one translation.
Visit Dynamic NAT lesson to learn how NAT translate Source IP Address.