A static IP address is a manually assigned IP address for a single device on a network. The network administrator configures the device such that it only uses a fixed IP address when it joins the network, hence the term static.
Most devices default to using dynamic IP addresses that are obtained via a DHCP server, as of 2014. However, there are instances when a static IP address is preferable, such as when a computer needs to directly receive emails, host a Web site or make VoIP calls. A static IP address is also useful for running FTP and gaming servers. Conversely, it may pose a threat to security, since an IP address that remains unchanged is an easier target for hackers.