In the POA film, you can see Dumbledore put out a candle with the wave of his hand, followed by the repeating of that action where the candle would light again.
Also, when Harry faces the Boggart!Dementor, you can see that after he loses concious. After Lupin helps him back up, you can see Lupin light the candles like Dumbledore did.
I know these are probably non-canonical because it was movie inventions, but do you think it could be plausible to do anyways?
Seeing that all young wizards and witches manage to perform some form of uncontrolled wandless magic prior to receiving their letter (and wands), yes, I think it's possible. Remember Harry blowing up Aunt Marge? However, I would imagine it wouldn't be as effective or as concentrated as with a wand.
A wand is a tool to channel magic. I've always imagined that a really talented wizard can probably do wandless magic quite controlled. However, I think you need a wand to perform a spell. I think wandless magic would involve a lot more focus and concentration, as you would really have to focus on what you want the effect to be. With a wand you can say a spell you don't know what means and get a result, like Harry did twice in HBP. I don't think you could do that without a wand. So I think it takes a rather powerful and controlled mind to be able to properly harness and control magic without a wand.
Must I come in and rant?
Alright, so I have to come and say that wandless magic is HIGHLY improbable in my opinion. I mean, like, freakish. I don't think it can really be controlled.
But hey, if it works for your story....
Well (as far as I know..) it will only be used here and there, just to light candles. I probably won't use it more than two or three times in my story.
I think that wandless magic is plausible, but not for "big" spells.
For example, Dumbledore can put out/light up a candle without a wand, but having him Stun someone is unrealistic.
If it was something little -- moving a small object, putting out or lighting candles, etc., then you should be alright, but ONLY if it's a semi-powerful wizard. Anything more elaborate or complex would require a wand.
Hope I helped.
I agree with everyone, small magical tasks can be done wandlessly (word?). But as I was just reading up on the Lexicon I came across an interesting bit that seems rather obvious now that I think about it. When being an Animagi one would assume that to transform one would need a wand, yes? I mean, it is rather advanced magic. But Sirius escapes Azkaban, wandless, as Padfoot. Huh, huh? Just food for thought.
But my point is that levitation, small summoning spells (ie. one's wand happens to be one foot from him or her and unable to move), lights out kind of things are plausible for wandless magic.
Well, Voldemort could—when he was only 11—perform spells without a wand. They might not have been powerful, but he was consciously doing magic. So, therefore, I think that someone like Dumbledore or Voldemort would be able to do some spells wandless—maybe even quite a few. For the most part, though, I don't think most wizards could channel their power without a wand. A few exceptions, but not for the most part.
Animagi don't use wands. However, the magic is channeled inward, affecting only their body and not some other outside object. And while Voldemort and Dumbledore might have been able to perform some controlled magic without a wand, they would represent the exception to the general rule.
Circumstances may also play a role. I'd imagine one could possibly throw up a shield without a wand, but only temporarily and under duress.
Lily also did wandless magic on purpose.
As for animagi, I don't think you need a wand to transform. Peter didn't take Remus' wand in PoA to turn into a rat, he took it so that he wouldn't be unarmed. Harder for anyone to stop him.
As stated above, I do believe in the consept of wandlewss magic, I just think it requires a great deal of concentration.