The gig economy is where large numbers of people are now working gigs.
We see many things also refer to gig cities and a gig city is something different than the gig economy although the gig cities may well support a larger gig economy. A gig city (or any other type locality is a city that has 1 gigabit speed or faster Internet available in it, although now some cities including Chattanooga are advertising, they are 10 gig cities. Most people have internet connections somewhere in the range of 20-200 megabit speeds but gig speeds are available in many places but much more expensive.
A gig economy is where people get a variety of short term and often part time jobs and at various locations instead of a single full-time job. So, they have a gig at XYZ Company.
In the computer area this is becoming more common as companies are hiring people to only come in and do a project and then leave. In reality this is not different than many jobs in our economy have been as many construction workers have worked this way. The person is hired either as an employee or a contractor or a project comes in and does it and then moves on to other work.
The gig economy works well for some people, but the stress of not knowing where you are working in 3 or months does not suit others. Usually the person gets more pay by doing short term and the company saves money of not having to find them something to do after project.
The gigabit Internet supports the economy in some ways as it allows more mall and new firms to pop up and produce items for the Internet or thru the Internet and they just need a large number of employees to produce that product.