Cryptocurrency works on blockchain technology. The latter consists of individual blocks of data that can contain information about anything. For example, transactions made in a certain cryptocurrency. Each block of data contains a link to the previous block - this is how a chain of blocks is created. Thanks to the encryption of information, the chain remains unchanged and hackers cannot change its data.
There are now thousands of cryptocurrencies. However, this is a very unstable and speculative investment. The prices of even the most popular of them are much more volatile than the value of other assets such as stocks. For example, in November 2021, Bitcoin reached its all-time high and cost about $67,000, and on May 12, its price collapsed to $26,000.