you can buy bitcoin using different exchanges, you can also buy bitcoin directly from a person if a person have some bitcoin and he is interesting to sell some of so you can buy bitcoin from him using an escrow for this purpose if you do not know the person personally.
I have heard of Circle but don't know how they work really I think they work like localbitcoin would. You can exchange cash for bitcoin that way too.No, Circle is not like LocalBitcoins, it is a proper legit company, it is regulated and complies fully with the law. However, you can only use credit/debit cards or a bank account to buy bitcoin and depending on your account level, you might have weekly purchase limits. On the plus side, it's super easy and super fast to buy Bitcoin with card and their fees are low. And your funds on Circle is insured
