AP is ability power. If an ability has a number in green when you hover over it, that means it scales off of AP.
AD is attack damage. If an ability is in orange when you over over it, that means it scales off of AD.
However, not all champions necessarily play based 100% on what they scale off of. Miss Fortune would probably look like an AP character to someone who didn't know her, yet she's AD. There are also champions who don't want to build AD or AP at all, in favor of building pure tank or something.
If there are any specific champions you're wondering about, you might as well ask about them and we can tell you. --- Winner of the Third Hacked User Contest. World's #1 Phoenix Wright fan.
Meta game asks for a bruiser (Tanky attack damage champ) solo top. An AP Carry (squishy, pure DD, usually ranged) mid. Bottom has an AD carry (same as AP carry but asks for Attack Damage stats) and a support (either stuns players or boosts the carry to secure kills). The fifth player is jungler who levels on the monsters between lanes and tries to periodically assist in killing a champ in a lane.
Low level games will usually replace the jungler with a double top lane. --- Sent from my iPhone via PowerFAQs 1.10
AD is attack damage. It usually means you heavily focusing on dealing damage through your auto attacks. AP is ability power. It usually means you heavily focus on dealing damage through your abilities/skills/spells
Damaging spells usually scale with either of those stats. That means in addition to it's base damage, it does more damage based on how much of each stat you have. Mostly every skill has some sort of scaling and has ratios on how much extra damage you'll do.
Example: Anivia's Q does 120 damage (+100%) of AP and you have a Rabadon's Deathcap (120AP) This means that your Q will do 120 + 120(Rabadon's) for a total of 240 damage (before resists)
The traditional roles in League are: AD Carry (Weak early game, babysat by support, monster late game) AP Mid/Carry (Decent early game, great mid game, falls off late game unless fed) Bruiser (Beefy but powerful character that tries to murder squishes) Jungler (Clears jungle and ganks other lanes to make it 2v1's or 3v2's) Assassin (Bursty squishy characters meant to take out the enemy's main damage) Support (Babysits the ADC, usually has heals or steroid abilities) Tanks(Damage soakers + Initiators) --- I'm the best player here. The rest of you aren't as good as me-ninja1357 LoL IGN: m0bilize (NA)
AP: Ability Power. AP carries are basically what LoL calls Mage. They go mid
AD: Attack Damage. AD carries can be ranged or melee. Anyone that looks like they're shooting arrows/bullets are AD ranged (Ashe, Miss Fortune etc). they go bot. AD melee are people with swords/axes basically. They go top usually.
Tanks: I hope you know what a tank is... Support: Someone who will help the AD/AP carries kill minions and obtain objectives by healing/making them better. They usually go bot with AD carry. Tanks come under this category
Jungler: Someone who kills the monsters in the jungle, then using the buffs from the monsters, goes in for ganks (ambushing lanes)
You'll lose enough games to eventually be placed with people your level, so don't worry about it. --- Not changing this sig until Walter Mondale is elected president. Currently Playing: Pepper II, Venture, Frogger