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Rebecca Zisser / Axios

Today is the 10th anniversary of the first Twitter hashtag. It was #barcamp, sent by former Google designer Chris Messina, in reference to a user-generated conferencing group he had helped create called BarCamp.

Why it matters: Hashtags have become a huge part of Internet culture and language. Jimmy Fallon and Justin Timberlake have famously spoofed Internet conversations via hashtag-only banter skits, and viral hashtags like #tbt (throwback Thursday) and #blessed have become integrated into everyday conversations in real life. Studies have suggested that nearly 3/4 of all internet users use hashtags to communicate. And hashtags have also spread to other Internet platforms, like Facebook, which adopted the feature in 2013.

Messina tweeted the hashtag as a recommendation for Twitter to create groups by automatically adding hyperlink metadata to any word that followed the "#" symbol. Twitter initially rejected the idea, saying hashtags were for "nerds," but eventually adopted the hashtag into its code in 2009.

A tweet previously embedded here has been deleted or was tweeted from an account that has been suspended or deleted.

New data from Twitter:

125 million hashtags are Tweeted per day on average.#ThrowbackThursday and #tbt have been Tweeted 120 million times and #ootd has been Tweeted over 2 million times.Five of the most-used hashtags over the past decade originate from fans tweeting during award shows. #MTVHottest, #MTVStars, #KCA, #iHeartAwards and #BestFanArmy have all been used over 3 billion times.The most Tweeted television show hashtag of all time is #TheWalkingDead and the most Tweeted about movie hashtag of all time is #StarWars. The most Tweeted global sporting event hashtag is the #WorldCup and The most Tweeted US sporting event is the #SuperBowl. The most Tweeted about league hashtag is #NFL and the most Tweeted team hashtag is #MUFC.

Go deeper

33 mins ago - Health

CDC prepares tougher testing rules for international travelers

Travelers with their luggage arrive at a COVID-19 testing location at the airport in Los Angeles, Calif., on Nov. 23, 2021. Photo: Frederic J. Brown/AFP via Getty Images

The Centers for Disease Control and Prevention said Tuesday night that it is working to impose stricter testing requirements for international travelers due to the spread of the new Omicron variant.

The big picture: The new rules would require all international travelers, regardless of vaccination status, to show a negative test taken a day before their flight to the U.S. Currently, the CDC says fully vaccinated travelers are allowed to show a test taken no more than three days before their departure, AP reports.

Republicans threaten to shut down government over vaccine mandates

Sen. Mike Lee (R-Utah) in the Capitol in November 2020. Photo: Joshua Roberts/Getty Images

Conservative Republicans in the House and Senate are planning to force a government shutdown Friday to deny funding needed to enforce the Biden administration's vaccine mandates on the private sector, according to Politico.

Why it matters: Congress has until the end of the week to pass a stopgap measure to extend funding into 2022, though objection from a small group of Republicans could shut down the government.

Electric car prices could go up before they come down

Illustration: Eniola Odetunde/Axios

The secret to affordable electric vehicles is cheaper batteries. But after years of falling prices, battery costs are now headed in the wrong direction.

Why it matters: Costlier batteries could drive up the price of electric vehicles — threatening the auto industry's transition away from fossil fuels, and, in turn, society's fight against climate change.