Joanna Dark is an agent with the Carrington Institute.
The time frame for her activities in roughly 20 years in the future although it is likely a tad more as we see considerable use of flying cars inside the city [tales were written in 2000 talking about events in 2023].
In this near-future world, "corporations control everything. In the name of domination, these sprawling organizations have recruited their own military forces to fight clandestine battles against one another---a war fought in the boardrooms and won in the shadows, with the public none the wiser". When we meet Dark initially, she is just concluding her training to become an operative with the large and extremely powerful Carrington Institute, founded and run by Daniel Carrington.
While Carrington has more than one set of opposition, by far its greatest nemesis is the even bigger and more deadly dataDyne, run by CEO Cassandra De Vries, a woman that is as cold as ice and totally willing to sacrifice innocents and her own people to accomplish her goals. Unscrupulous in the dictionary has her picture next to it. Most of the adventures we see Dark undertaking will have dataDyne somewhere in the picture causing trouble.
We learn that Dark is the sole child of Jack Dark, a fairly cold-blooded man who earns his living as a bounty-hunter. Dark's mother dies in childbirth and her father showed his resentment of Joanna early on. Still the younger Dark worked diligently to be close to him and father Dark started using her in his man-hunting when she was just becoming an adolescent. By the time she is 16, Dark is a fully trained hunter, all before she changes careers and goes to work for Carrington.
Dark is shown and described as having red shoulder-length hair (although sometimes a tad shorter) with "a distinctive blonde streak that was the result of a genetic quirk". She sports bright blue eyes with a pale complexion. She enjoys (and works very hard to maintain) a slender, athletic build. When she is not on a mission, she enjoys 'relaxing' by engaging in sports such as "rock-climbing, free running, dirt-biking, and grav boarding". On our introduction we find a Dark that is calm and level-headed with a reasonable amount of patience; later in a prequel set of adventures we see her a few years younger and far more apt to lose her cool.
According to the wiki on her adventures, "being a professional bounty hunter to a secret agent, Joanna is a highly skilled marksman, a lethal hand to hand combat fighter, and an expert pilot and driver. She has incredible reflexes and an ability to sniff out trouble. Her technical skills stretch as far as wiring up a charge, picking a lock, or hacking a basic system. She also has an innate ability at 'being who people want her to be', which has allowed her to become an expert at keeping a false identity".