The Division sets in the future New York City that includes massive open world environment and special PvP area called Dark Zone (Dark Zone is not instanced region). Most of the time as you explore New York City and complete missions, you can EXP to level up your character, but when you step into Dark Zone, you will gain a different form of EXP to increase your rank within Dark Zone.
"Every adversary we encounter in The Division is tied to a level, just as our agents are, so naturally those who are of a higher level are more difficult and pose a much greater threat. However, with every level up your agent becomes more powerful and gains access to more advanced technology, unlocking skill modifications along with talents to assist them with even greater challenges," says the Senior Game Designer Marcus Rosengren.
"Within the Dark Zone, players will collect an entirely new form of experience. Detached from the regular level experience, players gain Dark Zone experience more as a rank system rather than a level," Senior Game Designer Matthieu Delisle explains. With a higher rank you will gain access to superior equipment and crafting recipes at specific vendors. But if you die enough times in Dark Zone, you get your rank decreased.
As an agent, you have a lot of freedom to choose your playing style through talent specialization and skill modification. Whether you like to play solo, support a group of friends, or sit back and dish out damage with the biggest gun possible, each talent allows you to take that extra step needed toward specializing your playstyle.
You can learn more about skills and character progression at the official site.