Assistive Technology is defined by Cook and Hussey (1995) on page 5 as being
“Any item or piece of equipment or product system whether acquired commercially off the shelf, modified, or customized that is used to increase or improve functional capabilities of individuals with disabilities.”
For me this means that assistive technology is any kind of device that helps someone to function better at any task. I think that this definition includes all technology, including electronics (e.g. a Jelly-Bean) and non-electronics (e.g. a shoe horn).
An example of a type of assistive technology is a Jelly-Bean Switch.