Gateway
The technical meaning is a hardware or software set-up that translates between two dissimilar protocols, for example Prodigy has a gateway that translates between its internal, proprietary e-mail format and Internet e-mail format. Another, sloppier meaning of gateway is to describe any mechanism for providing access to another system, e.g. AOL might be called a gateway to the Internet.

GBps
Gigabyte per second. Currently, Gigabits per second is the fastest measure bandwidth, and is most commonly associated with high speed networks, such as Ethernet. A Gigabit equals 1 billion bits, or 1,000,000,000 bits.

Gigabit Ethernet
Gigabit Ethernet is the Ethernet standard implementation that runs at 1000Mbps.

Gigabyte
Often called a Gig or a GB, Equivalent to 1024 megabytes.

Gopher
A widely successful method of making menus of material available over the Internet. Gopher is a Client and Server style program, which requires that the user have a Gopher Client program. Although Gopher spread rapidly across the globe in only a couple of years, it has been largely supplanted by Hypertext, also known as WWW (World Wide Web). There are still thousands of Gopher Servers on the Internet and we can expect they will remain for a while.

GUI
Graphical User Interface. A way of interacting with the computer that relies on graphical symbols. Most often requires a mouse. It is less powerful then the command-line interface, but is more user friendly and is easier to learn for users without technical background.