Did you know the word meme is 41 years old?
Biologist and author Richard Dawkins has told Newsbeat he's unhappy with how the internet has defined memes as "pictures with words".
You might wonder what the 76-year-old has to do with them at all. But he actually coined the term.
Back in 1976 he referenced memes in his book The Selfish Gene.
For him, memes are ideas that spread from brain to brain - a bit like genes, they are replicated many times.
"I'm not going to use the term internet meme to refer to a picture with writing on it," he tells Newsbeat.
So what makes a good meme, if not a hilarious picture with a great caption?
Newsbeat has spent the past few weeks meeting the people using memes to launch careers, digest politics and explain things that normally make them feel uncomfortable.
For them, memes have created a new language both on, and offline.
"They [memes] just explain those things you can't explain," says Mercy - a 20-year-old from London.
Michael Boateng agrees. The 22-year-old says they help explain politics for him.
"There's a lot that will be turned into a meme during this election period - it's happening already," he says.
"Everything will be turned into a meme but I'm kind of glad it will because it makes things a lot easier to take and to process."
While a lot of meme sensations come from the US, there's a growing community creating them in the UK too.
Hackney's Finest is one of the biggest meme accounts in Britain.
Their account has more than 700,000 followers and makes memes based on growing up in inner cities.
The two founders run their Instagram account anonymously and told us anonymity is part of the charm of sharing memes.
"Try and trace the root of your favourite meme - you can't do it, but that's the fun of it," they say.
"A lot of people would think we want to be famous or have our faces shown, but we just want to bring people together through entertainment, it doesn't go any further than that."
But for some people, the speed and anonymity of memes has led to a new wave of cyber-bullying.
Earlier this year TV personality Katie Price launched a petition to make punishments for online abuse tougher.
Her son Harvey is frequently targeted by online trolls who use his disability to create vicious memes.
Craig Byrne, 30, also discovered the dark side of memes when his disability was used to make him the subject of one.
"My hands were tied - I was helpless," he tells Newsbeat.
"I just wanted to go to the person and say, 'Why are you doing that - why would you put that up?'"