Cyberspace is a virtual plane in the Sprawl Trilogy, where corporations and data thieves explore. It is an endless grid, with huge towers and symbols made out of data representing access points to small systems, typically corporate or criminal.
There is a group of people, referred to as "Console Cowboys", who explore Cyberspace (or NET), finding corporate and criminal systems to use Black-ICE (dangerous hacker programs that can kill people in real life) so they can steal data or drain money accounts. A simple explanation is they are essentially data thieves and hackers. their job is incredibly dangerous, not to mention illegal. They use Decks (console-like computers) and Trodes (these connect their conscious to the NET)
Their are multiple Console Cowboys mentioned in the Sprawl Trilogy. Some important ones are Henry Dorsett Case, Bobby Newmark, Automatic Jack, MycCoy Pauley (the Dixie Flatline) and Bobby Quine.