Don't forget, G is also an abbreviation for the SI prefix giga. It basically multiplies the connected unit's size by 10^9, or 1000000000, also known as a "billion" to many English-speaking people.

Some giga-units used in real-life examples:

• SI units
• A Boeing 747's mass is 0.4 Gg (giga-gram).
• A century is 3 Gs (giga-second).
• The Moon is 0.4 Gm (giga-metre) away from Earth.
• Other SI giga-units tend to be really huge and impractical.
.
• Non-SI
• The universe is about 14 Gyr (giga-year) old. The Earth was formed 5 Gyr ago.

When measuring memory sizes in computer science, as with kilo (k) and mega (M), giga has been reused as the power of two which is closest to the metric prefix. In the case of giga, it is 2^30 = 1073741824. This ambiguity of 7% is quite significant. A hard-drive manufacturer may advertise a "40 GB (gigabyte) drive" in the 10^9 sense, which works out to 3 GB less than the 2^30 sense. A new unambiguous prefix has been suggested: gibi (Gi), which is only 2^30.

G is the seventh letter of the English alphabet. The ASCII code for G is 71, and g is 103. This node brought to you by the letter G, obviously.
Related thingies:

F G H