Apparently the term "independent developer" is not universally understood. That's a sign of the times I guess. 

Here's a stab at a definition.

Software development does not have to be a corporate thing. Sometimes software is created by individuals working with one or two other people, or on their own. Software development can be an art, like writing or sculpture. Lots of the software you use was created this way.

This is the way the personal computer software market got started. With individuals creating products, bringing them to market, selling them in some fashion, maybe starting companies around it, maybe not. Depending on how successful they are. 

It's also how the web developer world got started. Tim Berners-Lee did the initial work on the web as an indie.  And independent developers are the backbone of the game industry. 

I am not talking about contractors, consultants, part-time employees. that's a completely different thing.

I am an independent developer. Have been most of my career. Lots of other people are.

When I talk about incentives for independent developers, these are the people I'm talking about.