Bitcoin Holiday Calendar
December
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Haters in Disbelief Day
November 28th, 2013
Bitcoin breaks four digits for the first time in 2013!
Bitcoin Holiday
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Coldcard makes its debut
December 14th, 2017
On this day in 2017, the world's most trusted and secure bitcoin hardware wallet, the Coldcard, is first released.
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HODL day
December 18th, 2013
On this day in 2013, a very drunk user on the bitcointalk.org forums decided to make a post about why he wasn't selling despite the falling price.

Read the original discussion, "I AM HODLING", here.
Bitcoin Holiday
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Diffie-Hellman dayBitcoin Whitepaper DayBitcoin's birthday!Proof of Keys DayGenesis Transaction DayBitcoin Pizza DayBitcoin Logo DaySilk Road DayAltcoin Genesis DayThe great bitcoin bubble of 2011Coinkite Was Born #140,900The death of Mt. Gox24 block rollbackThe Billion Dollar DayBitcoin ATM DayShitcoin DayFree Ross DayHaters in Disbelief DayHODL dayOpendime makes its debutThe Slaying of the BearWhaleThis is Gentlemen!Lightning Whitepaper DayBitconneeeeeeeeect!Gold Parity DayFirst Lightning payment on LTCNY Disagreement DayBitcoin Independence DaySegWit Lock-in DayActivation DayS2X Failure to Launch DayColdcard makes its debutLightning Pay DayLightning Pizza DayLightning Network TorchBitcoin Infinity DayCraig Wright is a Fraud DayMoscow timeMoscow TimeLaw declaring bitcoin legal tender in El Salvador passesBitcoin becomes legal tender in El Salvador