A cryptocurrency is a digital or virtual currency that is secured by cryptography,
which makes it nearly impossible to counterfeit or double-spend. Many
cryptocurrencies are decentralized networks based on blockchain technology — a
distributed ledger enforced by a disparate network of computers. A defining
feature of cryptocurrencies is that they are generally not issued by any central
authority, rendering them theoretically immune to government interference or
manipulation.


Cryptocurrencies are systems that allow for secure payments online which are
denominated in terms of virtual “tokens,” which are represented by ledger entries
internal to the system. “Crypto” refers to the various encryption algorithms and
cryptographic techniques that safeguard these entries, such as elliptical curve
encryption, public-private key pairs, and hashing functions.
The first blockchain-based cryptocurrency was Bitcoin, which still remains the
most popular and most valuable. Today, there are thousands of alternate
cryptocurrencies with various functions and specifications. Some of these are
clones or forks of Bitcoin, while others are new currencies that were built from
scratch.


Bitcoin was launched in 2009 by an individual or group known by the pseudonym
“Satoshi Nakamoto.”1 As of March 2021, there were over 18.6 million bitcoins in
circulation with a total market cap of around $927 billion.


Some of the competing cryptocurrencies spawned by Bitcoin’s success, known as
“altcoins,” include Litecoin, Peercoin, and Namecoin, as well as Ethereum, Cardano,
and EOS. Today, the aggregate value of all the cryptocurrencies in existence is
around $1.5 trillion—Bitcoin currently represents more than 60% of the total
value.