Bitcoin's price has soared above $10,000 for the first time since early 2018, a new milestone in the virtual currency's latest comeback.

The price has more than tripled since hitting rock-bottom last December around $3,200. That was after crashing from an all-time high around $19,500 in December 2017.

As always, it's difficult to be sure what drives changes in bitcoin's price. But one obvious candidate is Facebook's announcement of its own cryptocurrency, called Libra, earlier this week. Libra is a potential bitcoin competitor, but the announcement also brings added legitimacy to the overall cryptocurrency market.

Also, as the world's most valuable cryptocurrency, bitcoin frequently serves as a medium of exchange among other cryptocurrencies—much as the US dollar acts as the default medium of exchange for global trade. So the introduction of Facebook's new cryptocurrency next year—and perhaps copycat efforts down the road—could bolster bitcoin's value.

Bitcoin's rise is part of a broader cryptocurrency boom. Ether, the currency of the Ethereum network, is now worth more than $290, a 2019 record. Bitcoin Cash, Litecoin, Monero, and Dash are all at or near 2019 highs.