GPS Collars and Fences:

Popular brands like Halo Collar and SpotOn are examples of wireless containment systems that use satellites and GPS to create a virtual, invisible fence.SpotOn Collar

How does it work?

A collar, worn by the dog, is a GPS receiver and receives signals from multiple GPS satellites to determine the precise location.
A person walks the perimeter where you want the virtual fence with a special handheld device or smartphone app recording the GPS coordinates along the path. The boundary can also be traced on a digital map.
The system creates a ¨geofence¨ that the GPS collar recognizes.
As the dog moves around, the GPS collar constantly checks the dog’s location against the stored boundary.
Warning zone: If the dog approaches the boundary, the collar emits a warning signal (tone or vibration)
Correction Zone: If the dog crosses the boundary, the collar emits a stronger signal (vibration or static correction) to encourage the dog to return to the safe area, so that the uncomfortable stimulus stops.

How I thought GPS collars worked before researching this article.

Pros:

The boundary can be anywhere you want, as big as you want. You can take it with you camping, the lake house, you can even take it to Canada!
Easy to change and customize the geofence.
Costs less than a physical fence and is portable.
Can cover large areas.
Real time tracking and alerts about the dog´s location.
You can vary the strength of the static correction.

What the heck is static correction?

Companies that produce electronic collars use the term static correction because the sensation delivered by these collars is often likened to the feeling of static electricity, such as the mild shock you might feel when touching a metal object after walking on carpet. The term “static” refers to this mild electrical sensation.

Frankly, it sounds a lot better than ¨shock collar¨.

These collars are widely used for training, using the principles of negative reinforcement and positive punishment to correct an undesired behavior and decrease the likelihood of it occurring again.

They deliver an electric stimulus that can be adjusted in intensity and in the case of GPS collars, turned off completely (only a sound or vibration is used). The big benefit of the electronic training collars is that they can be used remotely.

Cons of the GPS Fence & Collars:

Battery lasts the day and must be recharged nightly.
Some require cellular service and app subscriptions (think monthly cost) for full features such as tracking and boundary alerts.
Requires training to be applied effectively and humanely. This training requires a commitment of time and consistency. A dog must be able to understand and know the desired behavior to avoid the unpleasant correction. It must be combined with positive reinforcement.
A changing geofence boundary may lead to a dog not knowing where the “safe area¨ is that they can go to to stop the negative sensation.