Cryptocurrency is a digital or virtual currency that uses cryptography for security and operates independently of a central bank. It is decentralized and operates on a peer-to-peer network, meaning that transactions are verified and recorded on a distributed ledger called the blockchain.

As for whether it is a safe investment, it's important to note that cryptocurrency is a highly volatile and speculative asset. Its value can fluctuate significantly in a short period of time, and there is no guarantee of its future performance. There have been instances of hacking, fraud, and scams in the cryptocurrency market, which can result in significant losses for investors.

That being said, some investors have seen significant gains in their cryptocurrency investments, especially in the early years of Bitcoin and other cryptocurrencies. However, it's important to approach cryptocurrency investments with caution and to do thorough research before making any investment decisions. It's also important to diversify your portfolio and only invest what you can afford to lose.