What qualifies as "hitting" with an attack?

[Deliverance]

Have been messing with a mounted build involving the use of Aid Another, and stumbled upon the question of whether you are assumed to "hit" with your attack when you perform the Aid Another action. This specifically relates to the Trip and Grab monster abilities that some Animal Companions get.

[The Archive]

Quote:

Aid Another

In melee combat, you can help a friend attack or defend by distracting or interfering with an opponent. If you're in position to make a melee attack on an opponent that is engaging a friend in melee combat, you can attempt to aid your friend as a standard action. You make an attack roll against AC 10. If you succeed, your friend gains either a +2 bonus on his next attack roll against that opponent or a +2 bonus to AC against that opponent's next attack (your choice), as long as that attack comes before the beginning of your next turn. Multiple characters can aid the same friend, and similar bonuses stack.

You can also use this standard action to help a friend in other ways, such as when he is affected by a spell, or to assist another character's skill check.

Quote for reference.

Given that it doesn't say a thing about hitting, and that grab and trip monster abilities need to hit to trigger, no.

[Komoda]

There is no way that an Aid Another of AC 10 allows you to grab an AC 45 creature.

[Hendelbolaf]

Aid Another on Attacks

Pros: You just need to hit an AC 10 not the actual AC and you give an ally +2 to hit

Cons: You do not do any damage or other effects to the foe

It is that simple. If you want to Trip or Grab, then attack normally and your ally will not get a +2 to hit as it is no longer an Aid Another.

[waiph]

If you use aid another you attack AC 10 and if you make AC 10 then the attack that you aided gets a plus 2. So the next attack gets a+2 bit the grab our trip roll, a second attack would get no benefit I think...

Have to check the rules for grab. Do you get +20 to the Grab grapple attempt via true strike?

[Starglim]

Since you have not necessarily hit the creature's touch AC and probably haven't hit its CMD, you have succeeded on your Aid Another attempt but nothing else.

[Eridan]

PRD wrote:

Grab (Ex) If a creature with this special attack hits with the indicated attack (usually a claw or bite attack), it deals normal damage and attempts to start a grapple ..

PRD wrote:

Trip (Ex) A creature with the trip special attack can attempt to trip its opponent as a free action without provoking an attack of opportunity if it hits with the specified attack.

Attacking (via attack or full-attack action) and Aid Another are totally different actions. Aid Another is not an attack. It is a special standard action with its own rules that dont interact in any ways with attacks or attack options.