It's a big day in the Wizarding World, so ... accio party hat! Wednesday marks 15 years since the first "Harry Potter" film opened in theaters.

Yes, it's hard to believe the big-screen adventure started so long ago, but it's true. On Nov. 16, 2001, "Harry Potter and the Sorcerer's Stone" first brought the beloved storybook characters off the page.

We've learned a lot from Harry and the gang since those early days, so we're celebrating 15 years of movie magic with a list of 15 of our favorite life lessons:

From the first film to the last, Daniel Radcliffe, Emma Watson and Rupert Grint made the Wizarding World magical. Warner Bros.

1. Choose your friends wisely

Harry went with his gut, rather than the advice of Draco Malfoy, when it came to picking his pals in his first year at Hogwarts, and those loyal friends remained by his side all the way to the final battle — and beyond.

2. A good teacher is a great thing

Hogwarts had plenty of amazing teachers who put their students' needs and safety first. And just like their real-world counterparts, we're sure they never made enough galleons, sickles and knuts to compensate them for all their hard work.

"Harry Potter and the Sorcerer's Stone" brought magic to the big screen in 2001. Warner Bros.

3. Face your fears

Whether it was as simple as saying a frightful name to take away its power or facing one giant spider — and a thousand little ones — confronting fears proved powerful in the Potterverse.

4. If you need help, ask for it

Harry had one flaw throughout every story: His first instinct when facing danger was to face it alone. But along the way, he always found out that a little help from his teachers, the groundskeeper and the headmaster — and a whole lot of help from his friends — was the only way to win.

Alan Rickman as Professor Snape in "Harry Potter and the Order of the Phoenix." ©Warner Bros/Courtesy Everett Collection / ©Warner Bros/Courtesy Everett C

5. People aren't always what they seem

From the first story to the last, Harry learned powerful lessons about people he thought he knew. For instance, Professor Quirrell seemed like a well-meaning member of the faculty, until Harry discovered the dark (lord) secret he kept under wraps. And despite seven years of doubting Professor Snape's motives, Harry learned the potions master was fighting for him all along.

6. Be a doer, not a dreamer

When faced with a mirror that brought one's ultimate fantasies into focus, Dumbledore told Harry: "It does not do to dwell on dreams and forget to live."

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7. Never mistake confidence for courage

Gilderoy Lockhart boasted about his brave feats in "Chamber of Secrets," but it was all a bunch of hot air. Want to see real bravery? Check out quiet Neville Longbottom, who mustered up the courage to stand up to his friends in the beginning and to help take down big bad Voldemort in the end.

Ralph Feinnes as Voldemort in "Harry Potter and the Deathly Hallows: Part 1." Everett Collection

8. Everyone dies, but some never really live

"Don't pity the dead," Dumbledore — or Harry's idea of the late headmaster — said in the final film. "Pity the living, and above all, all those who live without love."

9. Wealth is relative

Harry's bank vault was filled with mounds of gold galleons, while his best friend, Ron, barely scraped by. But Ron had family, and Harry considered him much richer for it.

10. The most harmful action is inaction

"Indifference and neglect often do much more damage than outright dislike," Dumbledore warned in "Order of the Phoenix."

Michael Gambon as Albus Dumbledore in "Harry Potter and the Goblet of Fire." Warner Bros.

11. Older doesn't mean wiser

So many of the best lessons are in Dumbledore's words, including his words about where wisdom is often found: "Age is foolish and forgetful when it underestimates youth."

12. It's OK to be a misfit

Luna Lovegood was roundly mocked for being fanciful and just plain out-there — even Hermione accidentally called her "Loony" once — but she was also a faithful friend to Harry and a worthy member of Dumbledore's Army.

13. The way to really know someone

Sirius Black said it best in "Goblet of Fire": “If you want to know what a man’s like, take a good look at how he treats his inferiors, not his equals."

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14. Death is inevitable, but love is immortal

Harry's mother died defending him, but her love lived on — and continued to protect him long after she was gone.

15. Magic is real

We may not have wands (or at least ones that work), but we have friends — and that's the most powerful force in the whole Wizarding World.

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