HODL is a meme used by Bitcoiners and other cryptocurrency users to describe a buy-and-hold strategy.  It came from a misspelling of the word “hold” on a forum post. 

On December 18 at 10:03 UTC , a user on the bitcoin forum bitcointalk.com posted an angry rant full of profanity and drunken clarity.  The title of the post was “I AM HODLING”

 

I type d that tyitle twice because I knew it was wrong the first time.  Still wrong.  w/e.  GF's out at a lesbian bar, BTC crashing WHY AM I HOLDING? I'LL TELL YOU WHY.  It's because I'm a bad trader and I KNOW I'M A BAD TRADER.  Yeah you good traders can spot the highs and the lows pit pat piffy wing wong wang just like that and make a millino bucks sure no problem bro.  Likewise the weak hands are like OH NO IT'S GOING DOWN I'M GONNA SELL he he he and then they're like OH GOD MY ASSHOLE when the SMART traders who KNOW WHAT THE FUCK THEY'RE DOING buy back in but you know what?  I'm not part of that group.  When the traders buy back in I'm already part of the market capital so GUESS WHO YOU'RE CHEATING day traders NOT ME~!  Those taunt threads saying "OHH YOU SHOULD HAVE SOLD" YEAH NO SHIT.  NO SHIT I SHOULD HAVE SOLD.  I SHOULD HAVE SOLD MOMENTS BEFORE EVERY SELL AND BOUGHT MOMENTS BEFORE EVERY BUY BUT YOU KNOW WHAT NOT EVERYBODY IS AS COOL AS YOU.  You only sell in a bear market if you are a good day trader or an illusioned noob.  The people inbetween hold.  In a zero-sum game such as this, traders can only take your money if you sell.

so i've had some whiskey
actually on the bottle it's spelled whisky
w/e
sue me
(but only if it's payable in BTC)

https://bitcointalk.org/index.php?topic=375643.0

The context for this post is just as important as the post itself.   In 2013 the price of bitcoin had rocketed from around $15 to over $1100.  On December 18 in the hours preceding the post Bitcoins price had fallen from by almost 40%.  This volatility had been and continues to be a characteristic of bitcoin, with frequent substantial drops in value.  This has led many to speculate and try to time the market movements.  Quite often amateur traders (and even many professionals) will misread, mistime or simply not understand the market and lose money. 

Within hours, the phrase “HODL” had been shared on stills from the move “300”, as the Leonidas character commands his soldiers to Hold.  And the meme has stuck with Bitcoin since.

Proponents of Bitcoin believe, that despite its continuing volatility, in the end adoption of Bitcoin by the masses will prevail and take the price “to the moon”.  As a result, the best plan would be to just buy and hold until that happens, rather than risking funds on short term trading strategies. 

Being a digital cryptocurrency, created and traded on the internet, it was inevitable that there are a number of memes created around bitcoin.  Other notable memes involve going “to the moon” meaning the price reaching an extraordinary high, “lambos” also feature quite often as a payoff for hodling, and the bitcoin rollercoaster guy(below) whose direction of travel is adjusted when posted depending on whether the market price is surging or dropping.