343i issued an update to their Halo blog today, this time focusing on the eight Specializations in Halo 4. This addition to the Halo multiplayer will allow players to focus their skills in a sort of class-based system. Unlockable armor mods raise your effectiveness based on your preferred role, though they aren't meant to make up for a lack of skill.
Right now, only two of the eight Specializations -- Wetwork and Pioneer -- will be available at launch. Once you've hit the standard 50 levels of multiplayer, you'll get to enlist in one Specialization for another ten. Since this is considered endgame content, 343 will be releasing more based on player milestones and progression.
Here are brief summaries for each Specialization, with much more details (and images) found on the Halo site:
Wetwork Specialization: Spartan optimization for stealth operations which focus on the elimination of an enemy target with the goal of leaving no tactical footprint behind.
Pioneer Specialization: Spartan optimization for deployment into uncharted, hostile territory (such as uncolonized worlds or Forerunner constructs like Requiem) for the purpose of gathering/relaying information.
Engineer Specialization: Spartan optimization for the subversion, repair and reconstitution of a wide range of technology, including Covenant and Forerunner complex networks.
Tracker Specialization: Spartan optimization for long-range target tracking (trans-continent and off-world), particularly in scenarios where conventional tracking has failed or such a substantial time has passed that the trail has gone cold.
Rogue Specialization: Spartan optimization for single-operative missions which require a lone Spartan to be deployed on their own for incredibly long durations of time, even years if required.
Stalker Specialization: Spartan optimization for target shadowing missions which require tactical invisibility despite operating at an extremely close range to the target itself.
Pathfinder Specialization: Spartan optimization for deep, unconventional deployment within unknown enemy territory and with little to no assistance from command.
Operator Specialization: Spartan optimization for the operation and control of a wide-range of vehicles; space, air, ground, and sea.