Interest in cryptocurrency was growing fast in 2021. The word “crypto” comes from cryptography, which is the technology that creates digital coins and keeps their transactions safe. Most cryptocurrencies run on decentralized networks. This means no single bank or government controls them.
That idea has also drawn criticism as crypto became more popular. But for many people, the main attraction is simple: a currency that is not run by one central authority.
At the time, Bitcoin was trading above $50,000, and the whole market was getting a lot of attention. Many well-known companies and banks were also paying close attention to digital assets. As Bitcoin rose, interest in “altcoins” (all coins other than Bitcoin) grew too, and many people wanted to know which ones would stand out.
This guide introduces ten popular cryptocurrencies from 2021, ranked by market capitalization (the total value of all coins). All prices and market caps below are a 2021 snapshot, so they are very different from today’s numbers. Use them to understand how these projects started, not as current prices.
1. Bitcoin (BTC)
Bitcoin was created by a person or group using the name Satoshi Nakamoto. The idea was described in a paper in 2008, and the network started in 2009. It is a decentralized digital currency that can be sent directly from one person to another over a peer-to-peer network. There is no single administrator or central bank.
Computers on the network, called nodes, check each transaction using cryptography. The transactions are then saved in a public record called a blockchain. Bitcoin has long been the biggest cryptocurrency, and it is the one most traders pay attention to. It also has high liquidity, which means it is generally easy to buy and sell.
To learn more about how it works, read our guide, Bitcoin Explained: Technology, Impact, and the Future of Finance.
2. Ethereum (ETH)
Ethereum is a software platform for building smart contracts and decentralized apps (DApps). A smart contract is a program that runs by itself when certain conditions are met, with no middleman needed.
The network is made up of many computers that agree on a growing chain of blocks, which are groups of transactions. Ether (ETH) is its native coin. In 2021, it was the second-largest cryptocurrency after Bitcoin.
Programmer Vitalik Buterin proposed Ethereum in 2013. The network went live on July 30, 2015, with an initial supply of about 72 million units.
3. Tether (USDT)
Tether launched in 2014, first under the name Realcoin. It is a “stablecoin,” which means it tries to keep a steady price. Tether aims to stay equal to one US dollar, unlike Bitcoin and Ethereum, whose prices can change a lot.
Tether says its coins are backed by reserves such as traditional currency held in bank accounts. How strong those reserves are has been debated over the years, so it is wise to read about the risks before using any stablecoin.
In January 2021, Tether was the third-largest cryptocurrency, with a market cap of about $24.4 billion.
4. Cardano (ADA)
Cardano is an open-source blockchain project that aims to support smart contracts. Its coin is called Ada. Charles Hoskinson, who also helped start Ethereum and BitShares, began designing the platform in 2015 and launched it in 2017. He left the Ethereum project after disagreements about its direction, and later helped build Cardano.
On March 29, 2021, ADA traded at about $1.19, with a market cap of about $40.4 billion.
5. Polkadot (DOT)
Polkadot is a proof-of-stake network that focuses on interoperability, which means different blockchains can work with each other. Its protocol connects both permissioned and permissionless blockchains, and also oracles, so they can share information in one environment.
Polkadot was developed by Gavin Wood, Robert Habermeier, and Peter Czaban. Gavin Wood is a co-founder and former Chief Technology Officer of Ethereum. Through the Polkadot relay chain, independent blockchains can exchange data and transactions without needing to trust each other.
As of March 2021, its market cap was about $30.3 billion, and one DOT was worth about $32.83.
6. Ripple (XRP)
Ripple appeared in 2012 as a digital payment network for financial transactions. XRP was created by Ripple Labs as the payment token for this system. XRP uses a network of validation nodes to confirm payments.
As of April 2, 2021, XRP had a market cap of about $26.8 billion, and one XRP traded at about $0.5926.
7. Uniswap (UNI)
Uniswap is a decentralized exchange protocol. It is also the name of the company that built it. The protocol lets people swap tokens on the Ethereum blockchain automatically, using smart contracts instead of a company in the middle.
As of April 2, 2021, its market cap was about $15.2 billion, and one UNI was worth about $29.21.
8. Litecoin (LTC)
Litecoin is an open-source cryptocurrency released under the MIT/X11 license. It is very similar to Bitcoin in its technical design, which makes it one of the earliest altcoins. The main difference is speed: Litecoin aims to create a new block every 2.5 minutes, while Bitcoin takes about 10 minutes. This means Litecoin confirms transactions faster.
As of April 2, 2021, its market cap was about $13.8 billion, and one LTC was worth about $206.75.
9. Chainlink (LINK)
Chainlink is a decentralized oracle network. In simple words, it helps smart contracts on Ethereum connect safely to outside data sources, APIs, and payment systems. The LINK token is used to power this network.
As of April 2, 2021, its market cap was about $12.8 billion, and one LINK was worth about $30.58.
10. Bitcoin Cash (BCH)
Bitcoin Cash was created in 2017 as a fork (a split) from Bitcoin. Its goal was to have a larger block size so that more transactions can fit in each block. It shares some technology with Bitcoin, such as the same type of consensus process and a supply limit of 21 million coins.
As of April 2, 2021, its market cap was about $10.8 billion, and one BCH was worth about $575.17.
Quick Summary Table
Coin |
Known for |
|---|---|
Bitcoin (BTC) |
First and largest cryptocurrency |
Ethereum (ETH) |
Smart contracts and DApps |
Tether (USDT) |
Stablecoin tied to the US dollar |
Cardano (ADA) |
Smart contract platform started by Charles Hoskinson |
Polkadot (DOT) |
Connecting different blockchains |
Ripple (XRP) |
Payments for financial transactions |
Uniswap (UNI) |
Decentralized token swapping |
Litecoin (LTC) |
Faster block times than Bitcoin |
Chainlink (LINK) |
Bringing real-world data to smart contracts |
Bitcoin Cash (BCH) |
Larger blocks than Bitcoin |
Final Thoughts
Cryptocurrency can grow quickly, but it can also fall quickly. Prices change often, rules differ between countries, and scams are common. Because of this, you should be very careful before investing. Never put in money you cannot afford to lose, do your own research, and learn how price swings work. Our beginner-friendly guide, How To Manage Crypto Volatility, can help you get started.

