Why do rockets have fins?

I show why rockets have fins but some don't

See the full video here:
I'll Show You What Happens When Rockets Don't Have Fins

[knightarora]

"Now you are all rocket scientist" Lets apply to the spacex career page.

[Angled]

It's actually impressive how much info you can cram into a short. Practically no word was wasted or extra, not even that last line, which was funny.

[jipillow]

When you ripped the fins off this became the elusive rocket surgery

[sgtrogers]

I am proud that I learned all this from KSP.

[mr.derpyface]

“Round is not scary, pointy is scary.”

[justinw.]

You've given me the confidence to ask my dog for a raise.

[WhatToCallMe]

You and Vsauce are the only people I want teaching me

[jaytheamazing]

In fact, very few rockets have fins at all. Atlas, Titan, Proton, Vulcan, New Glenn, Electron, and Falcon don’t or never did use fins

[darciek]

I’ve been watching u for a long time and I think u are an amazing YouTuber who makes great informative content. You are only getting better. Keep it up.

[SpeakerzMan_JBL]

y’know, i didn’t understand a single word he said but now i know to put fins on it so i’m now a rocket scientist

[loafofbreadx]

As someone who has spent years studying rocket science, this video is actually all you need!

[proghostzgamecreed]

"You are a rocket scientist, Harry"

[SmoothBrain]

Was that first rocket 🚀 a Tootsie roll bank? 😂😂😂😂

[BaberhamLincoln]

The real reason is that “Round is not scary, Pointy is scary” - Admiral General Aladeen

[ec]

The spacex rockets can't have fins because they have to land again after re-entry and need to be stable coming in right side up, even before thrust is applied. Without thrust, it would flip over so the fins are on top. That's why they have those deflector grates. They give great control coming in, but don't make the rocket do anything goofy during ascent

[Williamxmr]

In my fluid dynamics class we learned about nozzles and the kid sitting behind me said in this shocked voice “rocket science isn’t rocket science!”

He was right too

[mcdrippyyt]

It’s because of drag, which changes the center of pressure. The fins cause drag (resistance) towards the rear, making it push back against the air and force it to be at the back of whatever direction it’s heading towards, that’s why the front comes to a point, to give it the least amount of resistance so it can easily change its direction and always face forward

[carpetlayenful]

A low-budget indie video game taught me this stuff. The idea of the game in the start was to build model rockets out random model parts. Reaching heights if single story house. By the time I stopped playing the rockets were reaching mid stratosphere, in game.
Little to no instruction. Progressing required building more and more complex rockets. Building off the crumbs and knowledge gained from level before. It was addictive because it would mock you when you failed to build the new rockets. Even though a lot of the time, the rocket ideas were built on countering the flaws in the parts they provided.
LOL, of course it could have just been me.😅

[TheskinJak]

I work for a company that makes gimbal balancing, POI, MOI, and CG testing equipment- Raptor Scientific.
The CG and POI is so incredibly mission critical to these rockets that they won’t just turn, but a rocket headed for mars could just tumble and hit France or something. Everything could be specific to the mission, and it’ll all be for nothing without those measurements.

[snibdogg]

Now they can't say I'm a rocket scientist sarcastically anymore yay