Deus Ex's RPG roots allow different play styles based on how you choose to allocate experience points towards various skills. Since this is an action and espionage game, the skills available match the encounters you'll have. Take a look at the complete list, along with descriptions.

Computer	Upgrading this skill to Trained enables hacking. Hacking allows you to break into a computer terminal, security terminal, or ATM without having to know the password. When accessing the terminal an ICE Breaker will appear in the upper right corner. Click the HACK button to begin hacking. Upgrading your computer skill results in quicker hacking, allowing more time to be spent working with the hacked terminal before the ICE Breaker energy runs out. If you are not logged out when the ICE Breaker expires, you will be kicked out and suffer damage. If you are hacking an ATM, a higher computer skill will get you more credits from a hack if any are to be found.
Electronics	Anytime you use a multitool, this skill affects how many multitools are required to complete the action. Multitools enable you to accomplish a number of things including alarm switch deactivation, turret reprogramming, camera deactivation, security beam disabling, and keypad bypassing.
Environmental Training	Some equipment have a limited duration of use before they expire. How long the equipment lasts is affected by this skill. The higher your training, the longer the equipment lasts before expiration. Items affected by this skill include the rebreather, hazmat suit, ballistic armor, and thermoptic camo.
Lockpicking	Whenever you use your lockpicks, the amount needed is a combination of this skill and strength of the lock being picked. Better training in this skill lowers the number of lockpicks needed, but never less than one.
Medicine	A medkit normally heals 30 points of damage. Better training in this skill lets you heal more points per medkit.
Swimming	Denton's swimming abilities are just enough to avoid drowning. With training, Denton will be able to swim faster in water, making better use of his limited oxygen supply.
Weapons: Heavy Pistol Low-Tech Demolition Rifle	All weapons skills when upgraded will increase the damage dealt by all weapons in the class upgraded. With the exception of demolition, all weapons will aim quicker with upgrades. Mastering a weapon skill requires no aiming at all, where you fire is where the shot will go. Training in demolition increases the time you have to disarm a proximity placed grenade before it detonates.