Basic attack

An autoattack (also called standard, normal, or basic attack) is the attack performed by a champion when right-clicking an enemy unit. Autoattacks are also performed by an idle champion when an enemy unit ventures too close to it, or when the "attack move" function is used (default Shift + right-click ). Autoattacks are also performed by monsters, minions and turrets.

Champion
When using attack-move, the champion stops to attack any hostile that gets in their way en-route to a destination. If a champion has an attack target, they will continue to attack it if in range and will move closer to it when out of range, until either a new target is specified, a cancel order is issued (pressing the S key or by specifying another move order), or they lose vision of the target.

Minions
Minions will automatically attack their closest target by default, but may change targets in a similar manner to turrets. For more information see the behaviour of minions page.

Turrets
The behavior of turrets is described on the corresponding page as well as the damage of turrets autoattacks. Turret autoattacks differ from regular autoattacks by increasing damage. (Every consecutive turret autoattack deals slightly more damage than the last)

Vision
Autoattacking while hiding in brush or fog of war will reveal the attacking unit, and if in brush specifically will reveal allies, for a few seconds. Autoattacking while in stealth mode will break the stealth.

Damage
Autoattacks always deal physical damage unless one of the following abilities is used, in which case the whole damage of the autoattack will be magic damage. However, certain items, abilities or passives may cause them to deal additional magic damage on top of their base physical damage. Damage from autoattacks benefits from the attack damage stat on the attacker and are reduced by armor on the target.

When autoattacking a turret, the damage is based on the base attack damage added to either the bonus attack damage or 40% of a champion's ability power, depending on which one is higher. Even though it may use an  ability power  scaling on the auto attack, it still is entirely physical damage.

Attack Speed
The rate at which a champion attacks is called attack speed and is capped at 2.5; this means that a champion can attack at most, 5 times in a 2 second period.

Some abilities refresh the attack timer and allow a champion to attack again immediately if they use the ability after their autoattack.

A list of abilities that refresh the attack timer:

Permanently
Certain champion see there autoattack permanently empowered by their innate or abilities, such as :
 * Corki's autoattacks deal bonus true damage equal to.
 * Fizz's autoattack deal bonus magic damage equal to   over 3 seconds.
 * Nautilus's autoattacks deal bonus physical damage equal to 2 + (6 × level) and snare his target for seconds.
 * Orianna’s autoattacks deal bonus magic damage equal to.
 * Cho'Gath's autoattacks deal bonus magic damage equal to  in a line in front of him.
 * Taric's autoattacks deal bonus magic damage equal to 2% of his maximum mana. This bonus damage is doubled against champions.
 * Warwick's autoattacks deal bonus magic damage equal to /  /  and heal him for the same amount.
 * Miss Fortune's autoattacks deal extra magic damage on-hit. This damage cumulatively stacks up to 4 times on the same target if no more than 5 seconds pass between each hit for  to a maximum of  with full stacks.

Periodically
Certain champion see there autoattack periodically empowered by their innate or abilities, such as :
 * Every basic attack Caitlyn's next autoattack deals 150% damage to a champion or 250% damage to a minion or monster. Attacks from brush increase the attack counter by two instead of one. Headshot's counter does not increase from attacking turrets.
 * Every 3 basic attack Diana's next autoattack cleaves nearby enemies for 20 / 25 / 30 / 35 / 40 / 50 / 60 / 70 / 80 / 90 / 105 / 120 / 135 / 155 / 175 / 200 / 225 / 250 additional magic damage.
 * Every 10 seconds Nocturne's next autoattacks are enhanced, damaging surrounding enemies for and healing himself for  per enemy hit. Cooldown reduction does not affect Umbra Blades, but every basic attack reduces the cooldown by 1 second.
 * Every 9 seconds, Shen's next autoattack deals bonus magic damage equal to 4(4Shen's level) and restores energy to Shen. Cooldown reduction does not affect Ki Strike, but every basic attack reduces the cooldown by 1 second.
 * Every 12 seconds, Ziggs' next autoattack deals 13(7level) bonus magic damage. Cooldown reduction does not affect Short Fuse, but the cooldown is reduced by 4 seconds whenever Ziggs uses an ability. Short Fuse deals 50% bonus (150% total) damage to enemy structures.

Poison
Certain champion's autoattack poison their target, such as :
 * Gangplank's autoattacks apply a poison debuff for 3 seconds that can stack up to 3 times. Each stack deals 3(1level) magic damage per second and slows the target by 7%.
 * Twitch's autoattacks apply a stack of Deadly Venom, up to a maximum of 6 stacks. This venom deals true damage per stack, and will tick once per second for 6 seconds. Fully stacked, Deadly Venom deals  true damage per second for 6 seconds.