1. How you become friends: At 16, friendship is all about proximity. You become friends with the people you sit by in the most lessons at school. Twitter: @HarrieVerges And then you cement your friendship by talking on MSN all night. At 21, you make friends anywhere and everywhere: in halls, in lectures, in nightclub toilets... Flo Perry / BuzzFeed You're in a new chapter of your life, and you want to be friends with everyone. At 26, you make new friends at work. But you're still close with your school and uni friends too. Tap to play or pause GIF Tap to play or pause GIF Warner Bros. You end up with lots of little pockets of friends who sometimes meet each other on occasions like your birthday. 2. Where you hang out: At 16, you spend every weekend roaming your local high street, with a Starbucks Frappuccino in hand, and playing on Photo Booth at the Apple Store. Twitter: @austintelliott You make sure to visit all four floors of Debenhams. At 21, you either hang out in terrible student nightclubs, or slumped over your kitchen table nursing a horrific hangover. Tap to play or pause GIF Tap to play or pause GIF BBC And even though you should, you never hang out in the library. At 26, you host dinner parties that finish at a sensible time. Becky Barnicoat / BuzzFeed But you still drink lots of wine. 3. How you spend an average Friday night: At 16, Friday nights are reserved for sleepovers. Tap to play or pause GIF Tap to play or pause GIF FOX You watch horror movies, binge on Haribo, and crimp each other's hair. At 21, you go out every Friday night without fail. Twitter: @freddiehaines And the most fun part of every night out is the pregaming. At 26, you go out for a civilised dinner, as long as you're home by a reasonable time. FOX You need your eight hours sleep. 4. Which parties you have the most fun at: At 16, bowling followed by Pizza Hut is the best birthday party ever. Twitter: @b0ttlemen You go on the dance machines at bowling and then stir your Pizza Hut ice cream into mush. At 21, you go out clubbing multiple times a week. Twitter: @NecklacesFash And you drink enough Jägerbombs to keep you awake all night. At 26, you don't really go out anymore. But you do go to a new wedding every single weekend. Paramount Pictures Weddings are better than going out because they have free food, booze, and an overly emotional dad giving a speech. 5. What you eat together: At 16, it's all about sneaking out of school at lunchtime for a portion of McDonald's chips. Twitter: @NeilTheMacGuy There is no greater luxury. At 21, you scoff cheesy chips at the end of every single night out. View this photo on Instagram instagram.com The amount of food you can consume is almost impressive. At 26, you sometimes order so much takeaway that you have to lie on the floor with your jeans unzipped after you've finished. FOX And you never judge each other. 6. What you fight about: 7. At 16, the biggest fights are about who sits by whom on the school bus. Twitter: @Najwasfn If your best friend doesn't save you a seat, she's dead to you. 8. At 21, you fight about the people you fancy. Tap to play or pause GIF Tap to play or pause GIF MTV Snogging someone your friend once proclaimed they fancied causes a huge rift. At 26, you fight on behalf of your friend, not with her. HBO You'll defend her without even knowing what she did. 9. How often you hang out: At 16, you hang out every day at school, every Friday at a sleepover, and then every Saturday in town. Tabatha Leggett / BuzzFeed Where you'd always take this exact photograph. At 21, you still see each other every day, but that's because you live together. FOX You see each other in literally every state imaginable. At 26, you see your friends twice a month if you're lucky, but your group chat goes off all day, every day. ㅤ @FemaleBibIe If you are dating one of my girls just know that your arguments are displayed in our group chat and as a team we have written the response Mon Nov 30 15:00:03 UTC+0000 2015 Reply Retweet Favorite And you'll be there at the drop of a hat if your friends ever need you. 10. How many friends you have: At 16, you have a tightknit group of school friends who you do everything with. Tap to play or pause GIF Tap to play or pause GIF E4 You move as a pack. At 21, you have a massive group of friends you go out with and a few closer friends who know everything about you. Tap to play or pause GIF Tap to play or pause GIF E4 There are loads of people you will happily hang out with, but only a few who'll still be there as you vom into a taxi at the end of the night. At 26, you've cherry-picked your friends and you're left with a very small group of absolute babes. Tap to play or pause GIF Tap to play or pause GIF Universal Pictures You're too old for small talk, so the people you're friends with now are going to be stuck with you for life. 11. The kinds of favours you expect from your friends: At 16, you proofread your friends' UCAS applications at school and straighten their hair before a night out. Twitter: @timbolton1 You're there for each other through the highs and the lows. At 21, you check each other's dissertation references in the daytime and monitor each other's drunk texts at night. Warner Bros. Everyone has one friend who loves to send drunk declarations of love via text. And it's your job to stop that happening. 26-year-old friends are there to provide medical diagnoses, proofread job applications, and help compose sexy message at all times of day, no questions asked. View this post on Twitter: @chungswag And there's never any judgement. 12. The grossest thing you'd do for each other: At 16, you fake tan each other's bodies before every single house party. Twitter: @Hannahh_Robb Including the rude bits. Your early twenties are your grossest years. At 21, you'll happily hold your friend's hair back as they vom into a toilet. Warner Bros. Then you'll put them to bed, stick their phone on charge, and carry on with your night out. At 26, you've been through so much together that there's nothing you wouldn't do for each other anymore. Remee Patel / BuzzFeed / Getty Images What's hers is yours and what's yours is hers. 13. How you establish whether your friendship is for life: At 16, all the bonding happens at lunchtime. Paramount Pictures Every friendship group has a set area of the sixth form common room that they sit in to gossip. At 21, you bond over getting drunk and then surviving your hangover the next day. Flo Perry / BuzzFeed There's nothing like rehydrating together to cement a friendship. At 26, you bond over how shit men are. View this post on But srsly, why are they so bad?