Cryptocurrency is digital currency built on blockchain technology. Essentially, cryptocurrencies are decentralized and digital money or assets that can be used by anyone and sent freely and directly between people. The word "crypto" comes from the fact that the concept of cryptography is central to blockchain technology.
Yes. Cryptocurrency is legal. You have the right to buy and sell what you want, whether it is shares, crypto, used car or most other things. The only thing you need to keep in mind is to pay taxes if you sell your crypto at a profit.
Yes, cryptocurrency is taxable. You can read more about this here.
It depends on which cryptocurrency you invest in and when you bought it. Both Bitcoin and Ethereum have proven to be very good investments over the last 10 years. But prices can fluctuate a lot in the short term, and there are also other cryptocurrencies that have not been good investments. Think long term if you are going to invest in cryptocurrency. It is both safest and easiest.
Bitcoin is the first and largest cryptocurrency.
Cryptocurrencies are based on blockchain technology. They may work a little differently, but have the blockchain technology in common. You should start by reading about how Bitcoin works here. All the other cryptocurrencies build on the technology that came with Bitcoin.