Just like cash, bitcoin is used for everything from regular day-to-day business to criminal activities. However, unlike physical cash, the blockchain is permanent and immutable, which means anyone from a teen to the US government can follow every single transaction you make without you even knowing about it. However, there are ways to add layers of anonymity to your bitcoin transactions.
This is my first tutorial on this website. So, if you think anything to be wrong, just place it in the comments.