What is considered a fast internet speed?

Fiber optic cables provide the fastest Internet connections. Google Fiber and other similar companies have Internet plans that can give 1 gigabits-per-second download speeds. These plans are only available in certain cities, although more locations are continually added.
Scientists are experimenting with fiber optics that could enable potential download speeds of over 255 terabits per second, though these speeds are unlikely to reach consumer hands anytime soon.