Definition: Cryptocurrency is a digital form of money. This money is used as a medium of exchange through a computer network. Unlike traditional money, this is not controlled by banks or the government. The most famous cryptocurrency is bitcoin, created by a group known as Satoshi Nakamoto. After bitcoin, many cryptocurrencies have come to market.
How does it work? The working technology of cryptocurrency is blockchain technology. A blockchain is a digital ledger that records all transactions across a network of computers. As named, blockchain it defines the process.. Every Transaction is added to a block and then that block added to chain of previous transaction. This technology secures the transactions.
Why people like it?  The first main reason is that cryptocurrencies are not controlled by a single authority. Its not a traditional money so no bank and government control it. And this makes it more secure and reduces the risk or corruption and it kept users identity private. Sending money using cryptocurrency costs less then using other ways to International transfers. All u need just internet connection.
Challenges and problems: with benefits this also have some negative points also. Like government is still figuring out how to manage and regulate cryptocurrencies. People still feel risk to invest in them. The biggest negative point in cryptocurrency is its value changes quickly. Well we all know that blockchain is most secure technology but other parts of system, like exchanges and wallets  can be hacked, Which result huge lose. As more people start to use  cryptocurrency networks will became slow but solutions being developed such as lighting network.
Conclusion: at the end,  we can say cryptocurrency is very important innovation for future. Because its secure, transparent and easy to use. We have to adapt these changes as it could offers us new opportunities  in the world of finance.