Sure, Harry knows some far more advanced magical methods these days, but who could forget these classics from first year? And let’s not forget how important these spells would be later on in his life.
We never hear an incantation for the act of Transfiguration – changing something into something else – but it’s one of the first pieces of magic we witness in Philosopher’s Stone.
Professor McGonagall’s appearance as a cat is an act of Transfiguration, in a sense. Being an Animagus – having the ability to turn yourself into an animal – involves a lot of hard work, so while it’s not a spell in the wand-waving sense, it’s a powerful piece of transformative magic. We saw some proper Transfiguration magic when Hagrid gave Dudley a pig’s tail. Again it’s non-verbal, although it is accompanied by some help from Hagrid's mysteriously magical umbrella.
Ron is the first person we see attempting a verbal Transfiguration spell, when he tries to turn Scabbers' fur yellow. Unfortunately, we suspect Fred and George, who ‘taught’ Ron the spell, might’ve been joking.
As she’s Transfiguration teacher, it’s fitting that McGonagall shows us how it’s really done. During Harry’s first lesson, she turns her desk into an actual pig and back again – again, without any particular words.
This is the spell that nearly ended Hermione and Ron’s relationship way before it began, when Hermione went full know-it-all:
‘It’s Wing-gar-dium Levi-o-sa, make the “gar” nice and long.’
This spell is taught to first years in Professor Flitwick’s Charms class. When accompanied by the right wand movement, it causes objects to levitate. Obviously Hermione got it straight away, and Ron mercilessly mocked her for being a teacher's pet. However, when Hermione overheard Ron's cruel words and ran to the girl's bathroom for a little cry, Ron ended up using Wingardium Leviosa to save Hermione's life from a giant troll, who just so happened to be in the bathroom at the same time. What goes around comes around.
It’s also particularly handy when there are Death Eaters about, including:
The first time we hear this spell is when Hermione unlocks the third-floor corridor in a bid to avoid being caught out of bed.
Presumably Hermione learns Alohomora, otherwise known as the ‘thief’s friend’, in Charms. It certainly comes in useful – there are seven other instances of it being cast, including:
Also known as the Leg-Locker Curse, this spell is used on Neville by Malfoy, although we don’t know the incantation until Hermione whispers it to Ron. They plan to use it on Professor Snape if he attempts anything against Harry during a Quidditch match, but as it turns out, they don’t need to.
Locomotor Mortis doesn’t seem particularly popular, as the only other time it’s mentioned is when Harry uses it against Malfoy during a fight in Moaning Myrtle’s bathroom in Half-Blood Prince. The full Body-Bind, Petrificus Totalus, is probably more preferable, but more on that in a moment.
Poor Neville. He tries to do the right thing and stop Harry, Ron and Hermione leaving the common room at night, but all he gets is Hermione and the Petrificus Totalus spell, which leaves his entire body momentarily paralysed.
Hermione’s not the only one to try a Body-Bind Curse every now and then, though.
This spell becomes one of Hermione’s trademarks. We don’t hear the incantation for it in Philosopher’s Stone, but it could be a variation on Incendio.
Hermione first uses it against Snape when she and Ron think he is cursing Harry’s broom in his first Quidditch match. Her bright blue flames set Snape’s robes alight, before Hermione scoops them up and puts them into a jar.
This ingenious spell comes in very useful – in Philosopher’s Stone Hermione uses it to free Harry and Ron from Devil’s Snare, and much later it is an integral part of their Deathly Hallows travels.
And as the books unfolded, there would be plenty more where those came from.